Dedicated client-side signature generator in a networked storage system

ABSTRACT

A storage system according to certain embodiments includes a client-side signature repository that includes information representative of a set of data blocks stored in primary storage. During storage operations of a client, the system can generate signatures corresponding to data blocks that are being stored in primary storage. The system can store the generated signatures in the client-side signature repository along with information regarding the location of the corresponding data block within primary storage. As additional instances of the data block are stored in primary storage, the system can store the location of the additional instances in the client-side signature repository.

RELATED APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet, or any correction thereto,are hereby incorporated by reference into this application under 37 CFR1.57.

U.S. application Ser. No. 13/916,458 was filed concurrently with U.S.application Ser. No. 13/916,409, entitled COLLABORATIVE RESTORE IN ANETWORKED STORAGE SYSTEM, filed Jun. 12, 2013; U.S. application Ser. No.13/916,429 entitled RESTORE USING A CLIENT SIDE SIGNATURE REPOSITORY INA NETWORKED STORAGE SYSTEM, filed Jun. 12, 2013; U.S. application Ser.No. 13/916,385 entitled COLLABORATIVE BACKUP IN A NETWORKED STORAGESYSTEM, filed Jun. 12, 2013; U.S. application Ser. No. 13/916,434entitled BACKUP USING A CLIENT-SIDE SIGNATURE REPOSITORY IN A NETWORKEDSTORAGE SYSTEM, filed Jun. 12, 2013; and U.S. application Ser. No.13/916,467 entitled INTELLIGENT DATA SOURCING IN A NETWORKED STORAGESYSTEM filed Jun. 12, 2013; each of which is incorporated herein byreference.

BACKGROUND

Businesses worldwide recognize the commercial value of their data andseek reliable, cost-effective ways to protect the information stored ontheir computer networks while minimizing impact on productivity.Protecting information is often part of a routine process that isperformed within an organization.

A company might back up critical computing systems such as databases,file servers, web servers, and so on as part of a daily, weekly, ormonthly maintenance schedule. The company may similarly protectcomputing systems used by each of its employees, such as those used byan accounting department, marketing department, engineering department,and so forth.

Given the rapidly expanding volume of data under management, companiesalso continue to seek innovative techniques for managing data growth, inaddition to protecting data. For instance, companies often implementmigration techniques for moving data to lower cost storage over time anddata reduction techniques such as for reducing redundant data, pruninglower priority data, etc.

Enterprises also increasingly view their stored data as a valuableasset. Along these lines, customers are looking for solutions that notonly protect and manage, but also leverage their data. For instance,solutions providing data analysis capabilities, improved datapresentation and access features, and the like, are in increasingdemand.

SUMMARY

In response to these challenges, one technique developed by storagesystem providers is data deduplication. Deduplication typically involveseliminating or reducing the amount of redundant data stored andcommunicated within a storage system, improving storage utilization. Forexample, data can be divided into units of a chosen granularity (e.g.,files or sub-file data blocks). The sizes of the data blocks can be offixed or variable length. As new data enters the system, the data unitscan be checked to see if they already exist in the storage system. Ifthe data unit already exists, instead of storing and/or communicating aduplicate copy, the storage system stores and/or communicates areference to the existing data unit. Thus, deduplication can improvestorage utilization, system traffic (e.g., over a networked storagesystem), or both.

Even in those systems employing deduplication, data managementoperations, including backup and restore operations, can place heavydemands on available network bandwidth and available system resources.Such operations can also introduce significant delay due tocommunication latency between secondary storage (e.g., non-production,backup storage) and primary storage (e.g., production storage).

In accordance with certain aspects of the disclosure, one techniquedeveloped to address these challenges incorporates the use of aclient-side signature repository with a store of information including aset of signatures that correspond to data blocks stored in primarystorage, where the primary data is generated by applications running ona set of client machines. For instance, the client-side signaturerepository can include signatures of most, if not all, of the datablocks stored in primary storage and a reference to where copies of thedata block are located throughout the primary storage, similar to anindex in a book. In this manner, the system can identify signatures (andcorresponding data blocks) that are unique to primary storage (e.g., notfound in secondary storage) and otherwise track the data blocks thatreside in primary storage. In some cases, the client-side signaturerepository can be used to track the location of substantially all (e.g.,greater than 95 percent or greater than 99 percent) of the data blocksin primary storage. In yet other cases, the client-side signaturerepository can be used to track a smaller subset of the data blocks inprimary storage.

The client-side signature repository can generate and/or storesignatures and certain metadata associated with the primary data. Thesignature/metadata pairs are referred to as signature blocks in certainembodiments, as will be described. During copy operations (e.g., backup,replication, snapshot or other types of copy operations), restoreoperations, or other types of storage operations, the client-sidesignature repository can be queried to determine which data blocksreside in primary storage (which may also be referred to as productionstorage or as “client-side” storage) and which data blocks reside insecondary storage (which may also be referred to as non-productionstorage). In some embodiments, during a deduplicated backup or othercopy operation, the data blocks unique to primary storage are identifiedand sent to secondary storage, while only signature information or otherreference data is sent to secondary storage for data blocks that arealready located in secondary storage. In certain instances, during arestore, the data blocks unique to secondary storage are identified andretrieved from secondary storage, while the data blocks already locatedin primary storage are retrieved from primary storage.

The client-side signature repository can be used as part of a storagesystem to reduce the demands on the network between one or moreproduction clients generating and storing primary data andnon-production, secondary storage storing secondary copy data, such asbackup storage. For example, one or more client-side repositories canform part of the production client(s) or may share a common networktopology with the client(s), whereas the client(s) and the secondarystorage devices may be remote from one another or reside on differingnetwork topologies.

As just one example, the client-side signature repository and the clientmay communicate over a local area network (LAN), while client andsecondary storage communicate over a wide area network (WAN). Thus, theclient-side signature repository can communicate more effectively (e.g.,at a higher data transfer rate, more reliably, with less latency, etc.)with the client than the backup storage devices can communicate with theclient.

In some embodiments, each production client maintains a localclient-side signature repository including signature information, suchas signature information corresponding only to the data blocks in thatproduction client, or in alternative embodiments, signature informationcorresponding to multiple production clients. In certain embodiments,the primary storage subsystem (also sometimes referred to herein as“primary storage”) maintains a shared client-side signature repositoryincluding signature information that corresponds to data blocks storedacross some or all of the production clients. In this manner, a sharedclient-side signature repository can be a global map to all of the datablocks in primary storage.

Because the client-side signature repository in some embodiments storesthe signatures of all or substantially all of the data blocks located inprimary storage, the signatures and/or associated metadata can be usedto identify which data is already present in primary storage, withouthaving to read the actual data blocks themselves during theidentification process, thereby improving storage operation efficiency.For instance, during a restore operation, the secondary storagesubsystem (also sometimes referred to herein as “secondary storage”) cansend a set of signatures to primary storage for a data set that is to berestored to a client machine. In response, the primary storage subsystemconsults the signature information in the client-side signaturerepository, without reading the data blocks, to determine which datablocks are already present in primary storage.

Primary storage can include one or more signature generation componentsconfigured to generate the data block signatures stored in theclient-side signature repository. In some cases, each client maintainsits own signature generation module. For instance, each client-specificsignature generator can snoop or otherwise monitor data operations onthe corresponding client, and generate and send the signatures (andcorresponding metadata) to the client-side signature repository forstorage. Such a configuration can reduce network traffic within theprimary storage subsystem. In other cases, a shared signature generatorresides in primary storage (e.g., forms part of a central client-sidesignature repository) and is configured to generate signatures for allof the clients (or for at least a plurality of the clients).

The client-side signature repository can also be used to perform storageoperations in a collaborative fashion such that data from multipleclients is sourced for storage operations that don't necessarily involvethose clients. For instance, during a collaborative copy operation(e.g., a backup operation), in which the client-side signaturerepository is used during a secondary copy operation associated with atarget client, the client-side signature repository can identify whichof the multiple clients contain a copy of a particular data block in thecopy data set. A sourcing policy can include criteria for determiningwhich of the identified clients to source data blocks from. Based on thedesired sourcing policy, the data block to be used in a storageoperation can be retrieved from any one of the clients storing the copyof the subject data block, including the target client, or any otherclient. Moreover, during a collaborative restore operation fromsecondary storage to a target client, the client-side signaturerepository can be used to identify non-target clients that include datablocks in the restore data set, and to source the data blocks from thoseclients during the restore. Among other benefits, collaborative sourcingcan be used to reduce the amount of relatively high latency trafficbetween primary and secondary storage and to distribute storageoperation processing across the client machines in a desired fashion.Collaborative sourcing can also reduce the down time of the targetclient, or otherwise distribute processing load for deduplicationoperations.

In some embodiments, a method is provided for generating a backup dataset for a client computing device by using a signature repositoryresiding in a primary storage subsystem. The method can include for eachrespective client computing device of one or more client computingdevices in a primary storage subsystem, monitoring the storage of aplurality of files formed by data blocks generated by one or moresoftware applications running on the respective client computing device.The plurality of files are stored in a data store associated with therespective client computing device. The method can further includemaintaining, by a repository agent executing on one or more processorsin the primary storage subsystem, a repository indicating at least whichdata blocks of the monitored files are stored in the primary storagesubsystem. In response to instructions to create a secondary copy in asecondary storage subsystem of at least a subset of the plurality offiles stored in a data store associated with a first client computingdevice of the one or more client computing devices, the method caninclude querying the repository to identify at least a first group ofdata blocks that form at least a portion of the subset of files and forwhich matching data blocks are not stored in the secondary storagesubsystem, identifying the location of the first group of data blockswithin the primary storage subsystem, and retrieving the first group ofdata blocks from one or more of the data stores associated with the oneor more client computing devices.

In certain embodiments, a method is provided for generating a secondarycopy data set for a client computing device by collaboratively sourcingdata to be used in the secondary copy data set from at least one otherclient computing device. The method can include for each respectiveclient computing device of a plurality of client computing devices,monitoring storage of a plurality of files formed by data blocksgenerated by one or more software applications running on the respectiveclient computing device. The files are stored in a data store associatedwith the respective client computing device. The method can furtherinclude maintaining, by a signature repository agent executing on one ormore processors, a global mapping indicating which data blocks arestored in the data stores associated with each of the plurality ofclient computing devices. The separate copies of at least some of thedata blocks reside in the data stores of multiple ones of the pluralityof client computing devices. The method can further include in responseto instructions to create a secondary copy in secondary storage of atleast a subset of the plurality of files stored in the data store of afirst client computing device of the plurality of client computingdevices, querying, by the signature repository agent, the global mappingto identify at least a first group of data blocks in the subset of theplurality of files that are stored in the data store associated with asecond client computing device of the plurality of client computingdevices. The method can further include retrieving the first group ofdata blocks from the data store associated with the second clientcomputing device, and retrieving at least some of the remaining datablocks in the first portion from the data store associated with thefirst client computing device.

In some embodiments, a method is provided for restoring data to aprimary storage subsystem using data blocks residing in the primarystorage subsystem. The method can include maintaining data blocksignatures in a signature repository. The data block signaturescorrespond to at least unique signatures of data blocks that formprimary data. The primary data is generated by one or more applicationsexecuting on one or more of client computing devices. In addition, theprimary data for each respective client computing device of the one ormore client computing devices is stored in a data store associated withthe respective client computing device.

The method can further include receiving a set of data block signaturescorresponding to data blocks in a secondary copy of data maintained in asecondary storage subsystem. The secondary copy corresponding to aprevious version of the primary data of a first client computing deviceof the one or more client computing devices. The method can furtherinclude comparing, by one or more processors, the received set of datablock signatures to the data block signatures in the signaturerepository to determine which data blocks in the secondary copy alreadyreside in the primary storage subsystem, and restoring the secondarycopy to the data store associated with the first client computing deviceusing at least some of the data blocks in the secondary copy thatalready reside in the primary storage subsystem. The remaining datablocks in the secondary copy are retrieved from the secondary storagesubsystem.

In certain embodiments, a method is provided for restoring data to afirst client computing device located in a primary storage subsystemusing data blocks residing in a data store associated with a secondclient computing device located in the primary storage subsystem. Themethod can include maintaining in a signature repository data blocksignatures corresponding to data blocks that form primary data. Theprimary data generated by one or more applications executing on aplurality of client computing devices is located within the primarystorage subsystem, and the primary data for each respective clientcomputing device of the plurality of client computing devices is storedin a data store associated with the respective client computing device.The method can further include receiving a set of data block signaturescorresponding to data blocks in a secondary copy of data maintained in asecondary storage subsystem. The secondary copy of can correspond to aprevious version of the primary data of a first client computing deviceof the plurality of client computing devices.

The method can further include querying, using one or more processors,the signature repository to identify at least a first group of datablocks corresponding to a first group of data block signatures of thereceived set of data block signatures. The first group of data blocksare stored in the data store associated with a second client computingdevice of the plurality of client computing devices. The method canfurther include retrieving at least some of the first group of datablocks from the data store associated with the second client computingdevice, and restoring the secondary copy to the data store associatedwith the first client computing device using at least the data blocksretrieved from the second client computing device.

In some embodiments, a method is provided for maintaining a signaturerepository accessible by multiple client computing devices in a datastorage system. The method can include tracking storage of data unitscorresponding to primary data generated by one or more applicationsexecuting on a plurality of client computing devices that form a primarystorage subsystem. The primary data for each of the client computingdevices is stored in a data store associated with the respective clientcomputing device, and the primary storage subsystem is in communicationwith a secondary storage subsystem that is separate from the primarystorage subsystem and is configured to maintain secondary copies of atleast some of the primary data. The method can further includegenerating, by a signature agent executing on one or more processors inthe primary storage subsystem, signatures corresponding to the pluralityof tracked data units, and maintaining a signature repository includinga signature block for at least each unique signature of the generatedsignatures. Each signature block can include the unique signature, andone or data unit entries. Each entry can correspond to a copy of thedata unit associated with the unique signature that is stored in theprimary storage subsystem. Each entry can indicate which of theplurality of client computing devices stores the corresponding copy ofthe data unit. At least some of the signature blocks can include atleast a first entry indicating that a first client computing device ofthe plurality of client computing devices stores a copy of the data unitand a second entry indicating that a second client computing device ofthe plurality of client computing devices stores a copy of the dataunit.

In certain embodiments, a method is provided for sourcing data fromstorage associated with a pool of computing devices during a datastorage operation associated with one of the computing devices in thepool. The method can include obtaining signatures corresponding to dataunits that form a data set associated with a data storage operation. Thedata set can correspond to a version of primary data of a firstcomputing device in a pool of a plurality of computing devices. Eachrespective computing device in the pool can store primary data generatedby one or more software applications executing on the respectivecomputing device, and the primary data stored in at least one storagedevice can be associated with the respective computing device. Themethod can further include populating, by one or more processors, ashared signature repository. The shared signature repository can includesignatures corresponding to at least each unique data unit stored in thestorage devices of the computing devices in the pool. For each signatureincluded in the signature repository, an indication as to one or more ofthe computing devices whose at least one storage device can include acopy of the data unit corresponding to the signature. The method canfurther include comparing the obtained signatures with the signaturerepository to identify one or more of the computing devices in the poolwhose respective at least one storage devices include copies of dataunits in the data set, consulting, by one or more processors, a prioritypolicy; and based on the priority policy, and for at least some dataunits in the backup set, deciding to access copies of the at least somedata units from one or more computing devices in the pool other than thefirst computing device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a block diagram illustrating an exemplary informationmanagement system.

FIG. 1B is a detailed view of a primary storage device, a secondarystorage device, and some examples of primary data and secondary copydata.

FIG. 1C is a block diagram of an exemplary information management systemincluding a storage manager, one or more data agents, and one or moremedia agents.

FIG. 1D is a block diagram illustrating a scalable informationmanagement system.

FIG. 1E illustrates certain secondary copy operations according to anexemplary storage policy.

FIGS. 1F-1H are block diagrams illustrating suitable data structuresthat may be employed by the information management system.

FIGS. 1I and 1J are block diagrams that illustrate components of examplestorage systems configured to implement data management techniquesinvolving data block signature information and which are compatible withembodiments described herein.

FIG. 2A is a block diagram illustrative of an expanded view of anexemplary client-side repository.

FIG. 2B is a block diagram illustrative of an expanded view of anexemplary signature block stored within the client-side repository.

FIG. 3 is a flow diagram illustrative of one embodiment of a routineimplemented by a storage system for performing a secondary copyoperation using a client-side signature repository.

FIG. 4 is a state diagram illustrative of the interaction between thevarious components of an exemplary storage system with respect to anexemplary collaborative copy operation.

FIG. 5 is a flow diagram illustrative of one embodiment of a routineimplemented by a storage system for updating the client-side repositorywith data block signatures.

FIG. 6 is state diagram illustrative of the interaction between thevarious components of an exemplary storage system with respect to anexemplary copy operation involving a client-side signature repository.

FIG. 7 is a flow diagram illustrative of one embodiment of a routineimplemented by a storage system for executing a deduplicatedcollaborative copy operation using a client-side repository.

FIG. 8 is a flow diagram illustrative of one embodiment of a routineimplemented by a storage system for restoring data using a client-siderepository.

FIG. 9 is a state diagram illustrative of the interaction between thevarious components of an exemplary storage system with respect to anexemplary restore operation.

FIG. 10 is a state diagram illustrative of the interaction between thevarious components of an embodiment of a storage system with respect toan exemplary collaborative restore operation.

FIG. 11 is a flow diagram illustrative of one embodiment of a routineimplemented by a storage system for executing a collaborative restore ofdata using a client-side repository.

FIG. 12 is a flow diagram illustrative of one embodiment of a routineimplemented by a storage system for implementing a sourcing policy todetermine where to source data blocks for a storage operation.

FIG. 13 is a block diagram illustrative of an expanded view of anexemplary copy data set index stored within secondary storage.

FIG. 14 is a flow diagram illustrative of another embodiment of aroutine implemented by a storage system for executing a copy operation,where information relating to when entries in a client-side signaturerepository are updated is used to assist in the performance of the copyoperation.

DETAILED DESCRIPTION

Deduplication techniques designed to reduce the demands on storagesystems during backup and/or replication operations are described ingreater detail in the following U.S. patent applications, each of whichis incorporated by reference in its entirety. One or more embodiments ofthe present disclosure may be used with systems and methods disclosedtherein:

U.S. patent application Ser. No. 13/324,884, entitled “Client-SideRepository in a Networked Deduplicated Storage System,” and filed onDec. 13, 2011;

U.S. patent application Ser. No. 13/324,613, entitled “DistributedDeduplicated Storage System,” and filed on Dec. 13, 2011;

U.S. patent application Ser. No. 12/982,086, entitled “Content AlignedBlock-Based Deduplication,” filed Dec. 30, 2010;

U.S. patent application Ser. No. 12/982,100, entitled “Systems andMethods for Retaining and Using Block Signatures in Data ProtectionOperations,” filed Dec. 30, 2010

U.S. patent application Ser. No. 12/145,347, entitled “Application-Awareand Remote Single Instance Data Management,” filed Jun. 24, 2008;

U.S. patent application Ser. No. 12/145,342, entitled “Application-Awareand Remote Single Instance Data Management,” filed Jun. 24, 2008; and

U.S. patent application Ser. No. 12/725,288, entitled “Extensible DataDeduplication System and Method,” filed Mar. 16, 2010.

In addition, one or more embodiments of the present disclosure may alsobe used with systems and methods disclosed in the following patents,each of which is hereby incorporated herein by reference in itsentirety:

U.S. Pat. No. 7,389,311, entitled “Hierarchical Backup and RetrievalSystem,” issued Jun. 17, 2008;

U.S. Pat. No. 6,418,478, entitled “Pipelined High Speed Data TransferMechanism,” issued Jul. 9, 2002;

U.S. Pat. No. 7,035,880, entitled “Modular Backup and Retrieval SystemUsed in Conjunction with a Storage Area Network,” issued Apr. 25, 2006;

U.S. Pat. No. 6,542,972, entitled “Logical View and Access to PhysicalStorage in Modular Data and Storage Management System,” issued Apr. 1,2003;

U.S. Pat. No. 6,658,436, entitled “Logical View and Access to DataManage by a Modular Data and Storage Management System,” issued Dec. 2,2003;

U.S. Pat. No. 7,130,970, entitled “Dynamic Storage Device Pooling in aComputer System,” issued Oct. 10, 2006;

U.S. Pat. No. 7,246,207, entitled “System and Method for DynamicallyPerforming Storage Operations in a Computer Network,” issued Jul. 17,2007;

U.S. Pat. No. 7,454,569, entitled “Hierarchical System and Method forPerforming Storage Operations in a Computer Network,” issued Nov. 18,2008;

U.S. Pat. No. 7,613,748, entitled “System and Method for ContainerizedData Storage and Tracking,” issued Nov. 3, 2009; and

U.S. Pat. No. 7,620,710, entitled “Systems and Methods for PerformingMulti-Path Storage Operations,” issued Nov. 17, 2009.

Client-Side Repository Overview

Systems and methods are described herein for using deduplication andcollaborative data movement techniques to improve data storageoperations. Examples of such systems and methods are discussed infurther detail herein, e.g., with respect to FIGS. 1I-14. It will beappreciated that such techniques can be implemented by informationmanagement systems including those that will now be described withrespect to FIGS. 1A-1H. Moreover, the componentry for implementing thededuplication and data movement functionality shown and described withrespect to FIGS. 1I-14 can be incorporated into the informationmanagement systems of FIGS. 1A-1H, where applicable.

Information Management System Overview

With the increasing importance of protecting and leveraging data,organizations simply cannot afford to take the risk of losing criticaldata. Moreover, runaway data growth and other modern realities makeprotecting and managing data an increasingly difficult task. There istherefore a need for efficient, powerful, and user-friendly solutionsfor protecting and managing data.

Depending on the size of the organization, there are typically many dataproduction sources which are under the purview of tens, hundreds, oreven thousands of employees or other individuals. In the past,individual employees were sometimes responsible for managing andprotecting their data. A patchwork of hardware and software pointsolutions have been applied in other cases. These solutions were oftenprovided by different vendors and had limited or no interoperability.

Certain embodiments described herein provide systems and methods capableof addressing these and other shortcomings of prior approaches byimplementing unified, organization-wide information management. FIG. 1Ashows one such information management system 100, which generally caninclude combinations of hardware and software configured to protect andmanage data and metadata generated and used by the various computingdevices in the information management system 100.

The organization which employs the information management system 100 maybe a corporation or other business entity, non-profit organization,educational institution, household, governmental agency, or the like.

Generally, the systems and associated components described herein may becompatible with and/or provide some or all of the functionality of thesystems and corresponding components described in one or more of thefollowing U.S. patents and patent application publications assigned toCommVault Systems, Inc., each of which is hereby incorporated in itsentirety by reference herein:

-   -   U.S. Pat. No. 8,285,681, entitled “DATA OBJECT STORE AND SERVER        FOR A CLOUD STORAGE ENVIRONMENT, INCLUDING DATA DEDUPLICATION        AND DATA MANAGEMENT ACROSS MULTIPLE CLOUD STORAGE SITES”;    -   U.S. Pat. No. 8,307,177, entitled “SYSTEMS AND METHODS FOR        MANAGEMENT OF VIRTUALIZATION DATA”;    -   U.S. Pat. No. 7,035,880, entitled “MODULAR BACKUP AND RETRIEVAL        SYSTEM USED IN CONJUNCTION WITH A STORAGE AREA NETWORK”;    -   U.S. Pat. No. 7,343,453, entitled “HIERARCHICAL SYSTEMS AND        METHODS FOR PROVIDING A UNIFIED VIEW OF STORAGE INFORMATION”;    -   U.S. Pat. No. 7,395,282, entitled “HIERARCHICAL BACKUP AND        RETRIEVAL SYSTEM”;    -   U.S. Pat. No. 7,246,207, entitled “SYSTEM AND METHOD FOR        DYNAMICALLY PERFORMING STORAGE OPERATIONS IN A COMPUTER        NETWORK”;    -   U.S. Pat. No. 7,747,579, entitled “METABASE FOR FACILITATING        DATA CLASSIFICATION”;    -   U.S. Pat. No. 8,229,954, entitled “MANAGING COPIES OF DATA”;    -   U.S. Pat. No. 7,617,262, entitled “SYSTEM AND METHODS FOR        MONITORING APPLICATION DATA IN A DATA REPLICATION SYSTEM”;    -   U.S. Pat. No. 7,529,782, entitled “SYSTEM AND METHODS FOR        PERFORMING A SNAPSHOT AND FOR RESTORING DATA”;    -   U.S. Pat. No. 8,230,195, entitled “SYSTEM AND METHOD FOR        PERFORMING AUXILIARY STORAGE OPERATIONS”;    -   U.S. Pat. No. 7,315,923, entitled “SYSTEM AND METHOD FOR        COMBINING DATA STREAMS IN A STORAGE OPERATION”;    -   U.S. Pat. No. 8,364,652, entitled “CONTENT-ALIGNED, BLOCK-BASED        DEDUPLICATION”;    -   U.S. Pat. Pub. No. 2006/0224846, entitled “SYSTEM AND METHOD TO        SUPPORT SINGLE INSTANCE STORAGE OPERATIONS”;    -   U.S. Pat. Pub. No. 2010-0299490, entitled “BLOCK-LEVEL SINGLE        INSTANCING”;    -   U.S. Pat. Pub. No. 2009/0329534, entitled “APPLICATION-AWARE AND        REMOTE SINGLE INSTANCE DATA MANAGEMENT”;    -   U.S. Pat. Pub. No. 2012/0150826, entitled “DISTRIBUTED        DEDUPLICATED STORAGE SYSTEM”;    -   U.S. Pat. Pub. No. 2012/0150818, entitled “CLIENT-SIDE        REPOSITORY IN A NETWORKED DEDUPLICATED STORAGE SYSTEM”;    -   U.S. Pat. No. 8,170,995, entitled “METHOD AND SYSTEM FOR OFFLINE        INDEXING OF CONTENT AND CLASSIFYING STORED DATA”; and    -   U.S. Pat. No. 8,156,086, entitled “SYSTEMS AND METHODS FOR        STORED DATA VERIFICATION”.

The information management system 100 can include a variety of differentcomputing devices. For instance, as will be described in greater detailherein, the information management system 100 can include one or moreclient computing devices 102 and secondary storage computing devices106.

Computing devices can include, without limitation, one or more:workstations, personal computers, desktop computers, or other types ofgenerally fixed computing systems such as mainframe computers andminicomputers.

Other computing devices can include mobile or portable computingdevices, such as one or more laptops, tablet computers, personal dataassistants, mobile phones (such as smartphones), and other mobile orportable computing devices such as embedded computers, set top boxes,vehicle-mounted devices, wearable computers, etc. Computing devices caninclude servers, such as mail servers, file servers, database servers,and web servers.

In some cases, a computing device includes virtualized and/or cloudcomputing resources. For instance, one or more virtual machines may beprovided to the organization by a third-party cloud service vendor. Or,in some embodiments, computing devices can include one or more virtualmachine(s) running on a physical virtual machine host operated by theorganization. As one example, the organization may use one virtualmachine as a database server and another virtual or physical machine asa mail server. A virtual machine manager (VMM) (e.g., a Hypervisor) maymanage the virtual machines, and reside and execute on the virtualmachine host. Examples of techniques for implementing informationmanagement techniques in a cloud computing environment are described inU.S. Pat. No. 8,285,681, which is incorporated by reference herein.Examples of techniques for implementing information managementtechniques in a virtualized computing environment are described in U.S.Pat. No. 8,307,177, also incorporated by reference herein.

The information management system 100 can also include a variety ofstorage devices, including primary storage devices 104 and secondarystorage devices 108, for example. Storage devices can generally be ofany suitable type including, without limitation, disk drives, hard-diskarrays, semiconductor memory (e.g., solid state storage devices),network attached storage (NAS) devices, tape libraries or othermagnetic, non-tape storage devices, optical media storage devices,combinations of the same, and the like. In some embodiments, storagedevices can form part of a distributed file system. In some cases,storage devices are provided in a cloud (e.g., a private cloud or oneoperated by a third-party vendor). A storage device in some casescomprises a disk array or portion thereof.

The illustrated information management system 100 includes one or moreclient computing device 102 having at least one application 110executing thereon, and one or more primary storage devices 104 storingprimary data 112. The client computing device(s) 102 and the primarystorage devices 104 may generally be referred to in some cases as aprimary storage subsystem 117.

Depending on the context, the term “information management system” canrefer to generally all of the illustrated hardware and softwarecomponents. Or, in other instances, the term may refer to only a subsetof the illustrated components.

For instance, in some cases, the information management system 100generally refers to a combination of specialized components used toprotect, move, manage, manipulate, analyze, and/or process data andmetadata generated by the client computing devices 102. However, theinformation management system 100 in some cases does not include theunderlying components that generate and/or store the primary data 112,such as the client computing devices 102 themselves, the applications110 and operating system residing on the client computing devices 102,and the primary storage devices 104. As an example, “informationmanagement system” may sometimes refer to one or more of the followingcomponents and corresponding data structures: storage managers, dataagents, and media agents. These components will be described in furtherdetail below.

Client Computing Devices

There are typically a variety of sources in an organization that producedata to be protected and managed. As just one illustrative example, in acorporate environment such data sources can be employee workstations andcompany servers such as a mail server, a web server, or the like. In theinformation management system 100, the data generation sources includethe one or more client computing devices 102.

The client computing devices 102 may include any of the types ofcomputing devices described above, without limitation, and in some casesthe client computing devices 102 are associated with one or more usersand/or corresponding user accounts, of employees or other individuals.

The information management system 100 generally addresses & handles thedata management and protection needs for the data generated by theclient computing devices 102. However, the use of this term does notimply that the client computing devices 102 cannot be “servers” in otherrespects. For instance, a particular client computing device 102 may actas a server with respect to other devices, such as other clientcomputing devices 102. As just a few examples, the client computingdevices 102 can include mail servers, file servers, database servers,and web servers.

Each client computing device 102 may have one or more applications 110(e.g., software applications) executing thereon which generate andmanipulate the data that is to be protected from loss and managed.

The applications 110 generally facilitate the operations of anorganization (or multiple affiliated organizations), and can include,without limitation, mail server applications (e.g., Microsoft ExchangeServer), file server applications, mail client applications (e.g.,Microsoft Exchange Client), database applications (e.g., SQL, Oracle,SAP, Lotus Notes Database), word processing applications (e.g.,Microsoft Word), spreadsheet applications, financial applications,presentation applications, browser applications, mobile applications,entertainment applications, and so on.

The client computing devices 102 can have at least one operating system(e.g., Microsoft Windows, Mac OS X, iOS, IBM z/OS, Linux, otherUnix-based operating systems, etc.) installed thereon, which may supportor host one or more file systems and other applications 110.

As shown, the client computing devices 102 and other components in theinformation management system 100 can be connected to one another viaone or more communication pathways 114. The communication pathways 114can include one or more networks or other connection types including asany of following, without limitation: the Internet, a wide area network(WAN), a local area network (LAN), a Storage Area Network (SAN), a FibreChannel connection, a Small Computer System Interface (SCSI) connection,a virtual private network (VPN), a token ring or TCP/IP based network,an intranet network, a point-to-point link, a cellular network, awireless data transmission system, a two-way cable system, aninteractive kiosk network, a satellite network, a broadband network, abaseband network, a neural network, other appropriate wired, wireless,or partially wired/wireless computer or telecommunications networks,combinations of the same or the like. The communication pathways 114 insome cases may also include application programming interfaces (APIs)including, e.g., cloud service provider APIs, virtual machine managementAPIs, and hosted service provider APIs.

Primary Data and Exemplary Primary Storage Devices

Primary data 112 according to some embodiments is production data orother “live” data generated by the operating system and otherapplications 110 residing on a client computing device 102. The primarydata 112 is generally stored on the primary storage device(s) 104 and isorganized via a file system supported by the client computing device102. For instance, the client computing device(s) 102 and correspondingapplications 110 may create, access, modify, write, delete, andotherwise use primary data 112. In some cases, some or all of theprimary data 112 can be stored in cloud storage resources.

Primary data 112 is generally in the native format of the sourceapplication 110. According to certain aspects, primary data 112 is aninitial or first (e.g., created before any other copies or before atleast one other copy) stored copy of data generated by the sourceapplication 110. Primary data 112 in some cases is created substantiallydirectly from data generated by the corresponding source applications110.

The primary data 112 may sometimes be referred to as a “primary copy” inthe sense that it is a discrete set of data. However, the use of thisterm does not necessarily imply that the “primary copy” is a copy in thesense that it was copied or otherwise derived from another storedversion.

The primary storage devices 104 storing the primary data 112 may berelatively fast and/or expensive (e.g., a disk drive, a hard-disk array,solid state memory, etc.). In addition, primary data 112 may be intendedfor relatively short term retention (e.g., several hours, days, orweeks).

According to some embodiments, the client computing device 102 canaccess primary data 112 from the primary storage device 104 by makingconventional file system calls via the operating system. Primary data112 representing files may include structured data (e.g., databasefiles), unstructured data (e.g., documents), and/or semi-structureddata. Some specific examples are described below with respect to FIG.1B.

It can be useful in performing certain tasks to organize the primarydata 112 into units of different granularities. In general, primary data112 can include files, directories, file system volumes, data blocks,extents, or any other hierarchies or organizations of data objects. Asused herein, a “data object” can refer to both (1) any file that iscurrently addressable by a file system or that was previouslyaddressable by the file system (e.g., an archive file) and (2) a subsetof such a file (e.g., a data block).

As will be described in further detail, it can also be useful inperforming certain functions of the information management system 100 toaccess and modify metadata within the primary data 112. Metadatagenerally includes information about data objects or characteristicsassociated with the data objects.

Metadata can include, without limitation, one or more of the following:the data owner (e.g., the client or user that generates the data), thelast modified time (e.g., the time of the most recent modification ofthe data object), a data object name (e.g., a file name), a data objectsize (e.g., a number of bytes of data), information about the content(e.g., an indication as to the existence of a particular search term),to/from information for email (e.g., an email sender, recipient, etc.),creation date, file type (e.g., format or application type), lastaccessed time, application type (e.g., type of application thatgenerated the data object), location/network (e.g., a current, past orfuture location of the data object and network pathways to/from the dataobject), frequency of change (e.g., a period in which the data object ismodified), business unit (e.g., a group or department that generates,manages or is otherwise associated with the data object), aginginformation (e.g., a schedule, such as a time period, in which the dataobject is migrated to secondary or long term storage), boot sectors,partition layouts, file location within a file folder directorystructure, user permissions, owners, groups, access control lists[ACLs]), system metadata (e.g., registry information), combinations ofthe same or the other similar information related to the data object.

In addition to metadata generated by or related to file systems andoperating systems, some of the applications 110 and/or other componentsof the information management system 100 maintain indices of metadatafor data objects, e.g., metadata associated with individual emailmessages. Thus, each data object may be associated with correspondingmetadata. The use of metadata to perform classification and otherfunctions is described in greater detail below.

Each of the client computing devices 102 are generally associated withand/or in communication with one or more of the primary storage devices104 storing corresponding primary data 112. A client computing device102 may be considered to be “associated with” or “in communication with”a primary storage device 104 if it is capable of one or more of: routingand/or storing data to the particular primary storage device 104,coordinating the routing and/or storing of data to the particularprimary storage device 104, retrieving data from the particular primarystorage device 104, coordinating the retrieval of data from theparticular primary storage device 104, and modifying and/or deletingdata retrieved from the particular primary storage device 104.

The primary storage devices 104 can include any of the different typesof storage devices described above, or some other kind of suitablestorage device. The primary storage devices 104 may have relatively fastI/O times and/or are relatively expensive in comparison to the secondarystorage devices 108. For example, the information management system 100may generally regularly access data and metadata stored on primarystorage devices 104, whereas data and metadata stored on the secondarystorage devices 108 is accessed relatively less frequently.

In some cases, each primary storage device 104 is dedicated to anassociated client computing device 102. For instance, a primary storagedevice 104 in one embodiment is a local disk drive of a correspondingclient computing device 102. In other cases, one or more primary storagedevices 104 can be shared by multiple client computing devices 102,e.g., via a network such as in a cloud storage implementation. As oneexample, a primary storage device 104 can be a disk array shared by agroup of client computing devices 102, such as one of the followingtypes of disk arrays: EMC Clariion, EMC Symmetrix, EMC Celerra, DellEqualLogic, IBM XIV, NetApp FAS, HP EVA, and HP 3PAR.

The information management system 100 may also include hosted services(not shown), which may be hosted in some cases by an entity other thanthe organization that employs the other components of the informationmanagement system 100. For instance, the hosted services may be providedby various online service providers to the organization. Such serviceproviders can provide services including social networking services,hosted email services, or hosted productivity applications or otherhosted applications).

Hosted services may include software-as-a-service (SaaS),platform-as-a-service (PaaS), application service providers (ASPs),cloud services, or other mechanisms for delivering functionality via anetwork. As it provides services to users, each hosted service maygenerate additional data and metadata under management of theinformation management system 100, e.g., as primary data 112. In somecases, the hosted services may be accessed using one of the applications110. As an example, a hosted mail service may be accessed via browserrunning on a client computing device 102. The hosted services may beimplemented in a variety of computing environments. In some cases, theyare implemented in an environment having a similar arrangement to theinformation management system 100, where various physical and logicalcomponents are distributed over a network.

Secondary Copies and Exemplary Secondary Storage Devices

The primary data 112 stored on the primary storage devices 104 may becompromised in some cases, such as when an employee deliberately oraccidentally deletes or overwrites primary data 112 during their normalcourse of work. Or the primary storage devices 104 can be damaged orotherwise corrupted.

For recovery and/or regulatory compliance purposes, it is thereforeuseful to generate copies of the primary data 112. Accordingly, theinformation management system 100 includes one or more secondary storagecomputing devices 106 and one or more secondary storage devices 108configured to create and store one or more secondary copies 116 of theprimary data 112 and associated metadata. The secondary storagecomputing devices 106 and the secondary storage devices 108 maysometimes be referred to as a secondary storage subsystem 118.

Creation of secondary copies 116 can help in search and analysis effortsand meet other information management goals, such as: restoring dataand/or metadata if an original version (e.g., of primary data 112) islost (e.g., by deletion, corruption, or disaster); allowingpoint-in-time recovery; complying with regulatory data retention andelectronic discovery (e-discovery) requirements; reducing utilizedstorage capacity; facilitating organization and search of data;improving user access to data files across multiple computing devicesand/or hosted services; and implementing data retention policies. Theclient computing devices 102 access or receive primary data 112 andcommunicate the data, e.g., over the communication pathways 114, forstorage in the secondary storage device(s) 108.

A secondary copy 116 can comprise a separate stored copy of applicationdata that is derived from one or more earlier created, stored copies(e.g., derived from primary data 112 or another secondary copy 116).Secondary copies 116 can include point-in-time data, and may be intendedfor relatively long-term retention (e.g., weeks, months or years),before some or all of the data is moved to other storage or isdiscarded.

In some cases, a secondary copy 116 is a copy of application datacreated and stored subsequent to at least one other stored instance(e.g., subsequent to corresponding primary data 112 or to anothersecondary copy 116), in a different storage device than at least oneprevious stored copy, and/or remotely from at least one previous storedcopy. In some other cases, secondary copies can be stored in the samestorage device as primary data 112 and/or other previously storedcopies. For example, in one embodiment a disk array capable ofperforming hardware snapshots stores primary data 112 and creates andstores hardware snapshots of the primary data 112 as secondary copies116. Secondary copies 116 may be stored in relatively slow and/or lowcost storage (e.g., magnetic tape). A secondary copy 116 may be storedin a backup or archive format, or in some other format different thanthe native source application format or other primary data format.

In some cases, secondary copies 116 are indexed so users can browse andrestore at another point in time. After creation of a secondary copy 116representative of certain primary data 112, a pointer or other locationindicia (e.g., a stub) may be placed in primary data 112, or beotherwise associated with primary data 112 to indicate the currentlocation on the secondary storage device(s) 108.

Since an instance of a data object or metadata in primary data 112 maychange over time as it is modified by an application 110 (or hostedservice or the operating system), the information management system 100may create and manage multiple secondary copies 116 of a particular dataobject or metadata, each representing the state of the data object inprimary data 112 at a particular point in time. Moreover, since aninstance of a data object in primary data 112 may eventually be deletedfrom the primary storage device 104 and the file system, the informationmanagement system 100 may continue to manage point-in-timerepresentations of that data object, even though the instance in primarydata 112 no longer exists.

For virtualized computing devices the operating system and otherapplications 110 of the client computing device(s) 102 may executewithin or under the management of virtualization software (e.g., a VMM),and the primary storage device(s) 104 may comprise a virtual diskcreated on a physical storage device. The information management system100 may create secondary copies 116 of the files or other data objectsin a virtual disk file and/or secondary copies 116 of the entire virtualdisk file itself (e.g., of an entire .vmdk file).

Secondary copies 116 may be distinguished from corresponding primarydata 112 in a variety of ways, some of which will now be described.First, as discussed, secondary copies 116 can be stored in a differentformat (e.g., backup, archive, or other non-native format) than primarydata 112. For this or other reasons, secondary copies 116 may not bedirectly useable by the applications 110 of the client computing device102, e.g., via standard system calls or otherwise without modification,processing, or other intervention by the information management system100.

Secondary copies 116 are also in some embodiments stored on a secondarystorage device 108 that is inaccessible to the applications 110 runningon the client computing devices 102 (and/or hosted services). Somesecondary copies 116 may be “offline copies,” in that they are notreadily available (e.g. not mounted to tape or disk). Offline copies caninclude copies of data that the information management system 100 canaccess without human intervention (e.g. tapes within an automated tapelibrary, but not yet mounted in a drive), and copies that theinformation management system 100 can access only with at least somehuman intervention (e.g. tapes located at an offsite storage site).

The Use of Intermediate Devices for Creating Secondary Copies

Creating secondary copies can be a challenging task. For instance, therecan be hundreds or thousands of client computing devices 102 continuallygenerating large volumes of primary data 112 to be protected. Also,there can be significant overhead involved in the creation of secondarycopies 116. Moreover, secondary storage devices 108 may be specialpurpose components, and interacting with them can require specializedintelligence.

In some cases, the client computing devices 102 interact directly withthe secondary storage device 108 to create the secondary copies 116.However, in view of the factors described above, this approach cannegatively impact the ability of the client computing devices 102 toserve the applications 110 and produce primary data 112. Further, theclient computing devices 102 may not be optimized for interaction withthe secondary storage devices 108.

Thus, in some embodiments, the information management system 100includes one or more software and/or hardware components which generallyact as intermediaries between the client computing devices 102 and thesecondary storage devices 108. In addition to off-loading certainresponsibilities from the client computing devices 102, theseintermediate components can provide other benefits. For instance, asdiscussed further below with respect to FIG. 1D, distributing some ofthe work involved in creating secondary copies 116 can enhancescalability.

The intermediate components can include one or more secondary storagecomputing devices 106 as shown in FIG. 1A and/or one or more mediaagents, which can be software modules residing on correspondingsecondary storage computing devices 106 (or other appropriate devices).Media agents are discussed below (e.g., with respect to FIGS. 1C-1E).

The secondary storage computing device(s) 106 can comprise any of thecomputing devices described above, without limitation In some cases, thesecondary storage computing device(s) 106 include specialized hardwareand/or software componentry for interacting with the secondary storagedevices 108.

To create a secondary copy 116 involving the copying of data from theprimary storage subsystem 117 to the secondary storage subsystem 118,the client computing device 102 in some embodiments communicates theprimary data 112 to be copied (or a processed version thereof) to thedesignated secondary storage computing device 106, via the communicationpathway 114. The secondary storage computing device 106 in turn conveysthe received data (or a processed version thereof) to the secondarystorage device 108. In some such configurations, the communicationpathway 114 between the client computing device 102 and the secondarystorage computing device 106 comprises a portion of a LAN, WAN or SAN.In other cases, at least some client computing devices 102 communicatedirectly with the secondary storage devices 108 (e.g., via Fibre Channelor SCSI connections). In some other cases, one or more secondary copies116 are created from existing secondary copies, such as in the case ofan auxiliary copy operation, described in greater detail below.

Exemplary Primary Data and an Exemplary Secondary Copy

FIG. 1B is a detailed view showing some specific examples of primarydata stored on the primary storage device(s) 104 and secondary copy datastored on the secondary storage device(s) 108, with other components inthe system removed for the purposes of illustration. Stored on theprimary storage device(s) 104 are primary data objects including wordprocessing documents 119A-B, spreadsheets 120, presentation documents122, video files 124, image files 126, email mailboxes 128 (andcorresponding email messages 129A-C), html/xml or other types of markuplanguage files 130, databases 132 and corresponding tables or other datastructures 133A-133C).

Some or all primary data objects are associated with correspondingmetadata (e.g., “Meta1-11”), which may include file system metadataand/or application specific metadata. Stored on the secondary storagedevice(s) 108 are secondary copy data objects 134A-C which may includecopies of or otherwise represent corresponding primary data objects andmetadata.

As shown, the secondary copy data objects 134A-C can individuallyrepresent more than one primary data object. For example, secondary copydata object 134A represents three separate primary data objects 133C,122 and 129C (represented as 133C′, 122′ and 129C′, respectively).Moreover, as indicated by the prime mark (′), a secondary copy objectmay store a representation of a primary data object or metadatadifferently than the original format, e.g., in a compressed, encrypted,deduplicated, or other modified format.

Exemplary Information Management System Architecture

The information management system 100 can incorporate a variety ofdifferent hardware and software components, which can in turn beorganized with respect to one another in many different configurations,depending on the embodiment. There are critical design choices involvedin specifying the functional responsibilities of the components and therole of each component in the information management system 100. Forinstance, as will be discussed, such design choices can impactperformance as well as the adaptability of the information managementsystem 100 to data growth or other changing circumstances.

FIG. 1C shows an information management system 100 designed according tothese considerations and which includes: a central storage orinformation manager 140 configured to perform certain control functions,one or more data agents 142 executing on the client computing device(s)102 configured to process primary data 112, and one or more media agents144 executing on the one or more secondary storage computing devices 106for performing tasks involving the secondary storage devices 108. Whiledistributing functionality amongst multiple computing devices can havecertain advantages, in other contexts it can be beneficial toconsolidate functionality on the same computing device. As such, invarious other embodiments, one or more of the components shown in FIG.1C as being implemented on separate computing devices are implemented onthe same computing device. In one configuration, a storage manager 140,one or more data agents 142, and one or more media agents 144 are allimplemented on the same computing device. In another embodiment, one ormore data agents 142 and one or more media agents 144 are implemented onthe same computing device, while the storage manager is implemented on aseparate computing device.

Storage Manager

As noted, the number of components in the information management system100 and the amount of data under management can be quite large. Managingthe components and data is therefore a significant task, and a task thatcan grow in an often unpredictable fashion as the quantity of componentsand data scale to meet the needs of the organization.

For these and other reasons, according to certain embodiments,responsibility for controlling the information management system 100, orat least a significant portion of that responsibility, is allocated tothe storage manager 140.

By distributing control functionality in this manner, the storagemanager 140 can be adapted independently according to changingcircumstances. Moreover, a computing device for hosting the storagemanager 140 can be selected to best suit the functions of the storagemanager 140. These and other advantages are described in further detailbelow with respect to FIG. 1D.

The storage manager 140 may be a software module or other application.The storage manager generally initiates, performs, coordinates and/orcontrols storage and other information management operations performedby the information management system 100, e.g., to protect and controlthe primary data 112 and secondary copies 116 of data and metadata.

As shown by the dashed, arrowed lines, the storage manager 140 maycommunicate with and/or control some or all elements of the informationmanagement system 100, such as the data agents 142 and media agents 144.Thus, in certain embodiments, control information originates from thestorage manager 140, whereas payload data and payload metadata isgenerally communicated between the data agents 142 and the media agents144 (or otherwise between the client computing device(s) 102 and thesecondary storage computing device(s) 106), e.g., at the direction ofthe storage manager 140. Control information can generally includeparameters and instructions for carrying out information managementoperations, such as, without limitation, instructions to perform a taskassociated with an operation, timing information specifying when toinitiate a task associated with an operation, data path informationspecifying what components to communicate with or access in carrying outan operation, and the like. Payload data, on the other hand, can includethe actual data involved in the storage operation, such as content datawritten to a secondary storage device 108 in a secondary copy operation.Payload metadata can include any of the types of metadata describedherein, and may be written to a storage device along with the payloadcontent data (e.g., in the form of a header).

In other embodiments, some information management operations arecontrolled by other components in the information management system 100(e.g., the media agent(s) 144 or data agent(s) 142), instead of or incombination with the storage manager 140.

According to certain embodiments, the storage manager provides one ormore of the following functions:

-   -   initiating execution of secondary copy operations;    -   managing secondary storage devices 108 and inventory/capacity of        the same;    -   reporting, searching, and/or classification of data in the        information management system 100;    -   allocating secondary storage devices 108 for secondary storage        operations;    -   monitoring completion of and providing status reporting related        to secondary storage operations;    -   tracking age information relating to secondary copies 116,        secondary storage devices 108, and comparing the age information        against retention guidelines;    -   tracking movement of data within the information management        system 100;    -   tracking logical associations between components in the        information management system 100;    -   protecting metadata associated with the information management        system 100; and    -   implementing operations management functionality.

The storage manager 140 may maintain a database 146 ofmanagement-related data and information management policies 148. Thedatabase 146 may include a management index 150 or other data structurethat stores logical associations between components of the system, userpreferences and/or profiles (e.g., preferences regarding encryption,compression, or deduplication of primary or secondary copy data,preferences regarding the scheduling, type, or other aspects of primaryor secondary copy or other operations, mappings of particularinformation management users or user accounts to certain computingdevices or other components, etc.), management tasks, mediacontainerization, or other useful data. For example, the storage manager140 may use the index 150 to track logical associations between mediaagents 144 and secondary storage devices 108 and/or movement of datafrom primary storage devices 104 to secondary storage devices 108. Forinstance, the storage manager index 150 may store data associating aclient computing device 102 with a particular media agent 144 and/orsecondary storage device 108, as specified in a storage policy.

Administrators and other employees may be able to manually configure andinitiate certain information management operations on an individualbasis. But while this may be acceptable for some recovery operations orother relatively less frequent tasks, it is often not workable forimplementing on-going organization-wide data protection and management.

Thus, the information management system 100 may utilize informationmanagement policies 148 for specifying and executing informationmanagement operations (e.g., on an automated basis). Generally, aninformation management policy 148 can include a data structure or otherinformation source that specifies a set of parameters (e.g., criteriaand rules) associated with storage or other information managementoperations.

The storage manager database 146 may maintain the information managementpolicies 148 and associated data, although the information managementpolicies 148 can be stored in any appropriate location. For instance, astorage policy may be stored as metadata in a media agent database 152or in a secondary storage device 108 (e.g., as an archive copy) for usein restore operations or other information management operations,depending on the embodiment. Information management policies 148 aredescribed further below.

According to certain embodiments, the storage manager database 146comprises a relational database (e.g., an SQL database) for trackingmetadata, such as metadata associated with secondary copy operations(e.g., what client computing devices 102 and corresponding data wereprotected). This and other metadata may additionally be stored in otherlocations, such as at the secondary storage computing devices 106 or onthe secondary storage devices 108, allowing data recovery without theuse of the storage manager 140.

As shown, the storage manager 140 may include a jobs agent 156, a userinterface 158, and a management agent 154, all of which may beimplemented as interconnected software modules or application programs.

The jobs agent 156 in some embodiments initiates, controls, and/ormonitors the status of some or all storage or other informationmanagement operations previously performed, currently being performed,or scheduled to be performed by the information management system 100.For instance, the jobs agent 156 may access information managementpolicies 148 to determine when and how to initiate and control secondarycopy and other information management operations, as will be discussedfurther.

The user interface 158 may include information processing and displaysoftware, such as a graphical user interface (“GUI”), an applicationprogram interface (“API”), or other interactive interface through whichusers and system processes can retrieve information about the status ofinformation management operations (e.g., storage operations) or issueinstructions to the information management system 100 and itsconstituent components.

Via the user interface 158, users may optionally issue instructions tothe components in the information management system 100 regardingperformance of storage and recovery operations. For example, a user maymodify a schedule concerning the number of pending secondary copyoperations. As another example, a user may employ the GUI to view thestatus of pending storage operations or to monitor the status of certaincomponents in the information management system 100 (e.g., the amount ofcapacity left in a storage device).

The storage manager 140 may also track information that permits it toselect, designate, or otherwise identify content indices, deduplicationdatabases, or similar databases or resources or data sets within itsinformation management “cell” (or another cell) to be searched inresponse to certain queries. Such queries may be entered by the user viainteraction with the user interface 158. An information management cellmay generally include a logical and/or physical grouping of acombination of hardware and software components associated withperforming information management operations on electronic data. Forinstance, the components shown in FIG. 1C may together form aninformation management cell. Multiple cells may be organizedhierarchically. With this configuration, cells may inherit propertiesfrom hierarchically superior cells or be controlled by other cells inthe hierarchy (automatically or otherwise). Alternatively, in someembodiments, cells may inherit or otherwise be associated withinformation management policies, preferences, information managementmetrics, or other properties or characteristics according to theftrelative position in a hierarchy of storage operation cells. Cells mayalso be delineated and/or organized hierarchically according tofunction, geography, architectural considerations, or other factorsuseful or desirable in performing information management operations. Afirst cell may represent a geographic segment of an enterprise, such asa Chicago office, and a second storage operation cell may represent adifferent geographic segment, such as a New York office. Other cells mayrepresent departments within a particular office. Where delineated byfunction, a first cell may perform one or more first types ofinformation management operations (e.g., one or more first types ofsecondary or other copies), and a second cell may perform one or moresecond types of information management operations (e.g., one or moresecond types of secondary or other copies).

In general, the management agent 154 allows multiple informationmanagement cells 100 to communicate with one another. For example, theinformation management system 100 in some cases may be one informationmanagement cell of a network of multiple cells adjacent to one anotheror otherwise logically related in a WAN or LAN. With this arrangement,the cells may be connected to one another through respective managementagents 154.

For instance, the management agent 154 can provide the storage manager140 with the ability to communicate with other components within theinformation management system 100 (and/or other cells within a largerinformation management system) via network protocols and applicationprogramming interfaces (“APIs”) including, e.g., HTTP, HTTPS, FTP, REST,virtualization software APIs, cloud service provider APIs, and hostedservice provider APIs. Inter-cell communication and hierarchy isdescribed in greater detail in U.S. Pat. No. 7,035,880, which isincorporated by reference herein.

Data Agents

As discussed, a variety of different types of applications 110 canreside on a given client computing device 102, including operatingsystems, database applications, e-mail applications, and virtualmachines, just to name a few. And, as part of the process of creatingand restoring secondary copies 116, the client computing devices 102 maybe tasked with processing and preparing the primary data 112 from thesevarious different applications 110. Moreover, the nature of theprocessing/preparation can differ across clients and application types,e.g., due to inherent structural and formatting differences betweenapplications 110.

The one or more data agent(s) 142 are therefore advantageouslyconfigured in some embodiments to assist in the performance ofinformation management operations based on the type of data that isbeing protected, at a client-specific and/or application-specific level.

The data agent 142 may be a software module or component that isgenerally responsible for managing, initiating, or otherwise assistingin the performance of information management operations. For instance,the data agent 142 may take part in performing data storage operationssuch as the copying, archiving, migrating, replicating of primary data112 stored in the primary storage device(s) 104. The data agent 142 mayreceive control information from the storage manager 140, such ascommands to transfer copies of data objects, metadata, and other payloaddata to the media agents 144.

In some embodiments, a data agent 142 may be distributed between theclient computing device 102 and storage manager 140 (and any otherintermediate components) or may be deployed from a remote location orits functions approximated by a remote process that performs some or allof the functions of data agent 142. In addition, a data agent 142 mayperform some functions provided by a media agent 144, or may performother functions such as encryption and deduplication.

As indicated, each data agent 142 may be specialized for a particularapplication 110, and the system can employ multiple application-specificdata agents 142, each of which may perform information managementoperations (e.g., perform backup, migration, and data recovery)associated with a different application 110. For instance, differentindividual data agents 142 may be designed to handle Microsoft Exchangedata, Lotus Notes data, Microsoft Windows file system data, MicrosoftActive Directory Objects data, SQL Server data, SharePoint data, Oracledatabase data, SAP database data, virtual machines and/or associateddata, and other types of data.

A file system data agent, for example, may handle data files and/orother file system information. If a client computing device 102 has twoor more types of data, one data agent 142 may be used for each data typeto copy, archive, migrate, and restore the client computing device 102data. For example, to backup, migrate, and restore all of the data on aMicrosoft Exchange server, the client computing device 102 may use oneMicrosoft Exchange Mailbox data agent 142 to backup the Exchangemailboxes, one Microsoft Exchange Database data agent 142 to backup theExchange databases, one Microsoft Exchange Public Folder data agent 142to backup the Exchange Public Folders, and one Microsoft Windows FileSystem data agent 142 to backup the file system of the client computingdevice 102. In such embodiments, these data agents 142 may be treated asfour separate data agents 142 even though they reside on the same clientcomputing device 102.

Other embodiments may employ one or more generic data agents 142 thatcan handle and process data from two or more different applications 110,or that can handle and process multiple data types, instead of or inaddition to using specialized data agents 142. For example, one genericdata agent 142 may be used to back up, migrate and restore MicrosoftExchange Mailbox data and Microsoft Exchange Database data while anothergeneric data agent may handle Microsoft Exchange Public Folder data andMicrosoft Windows File System data.

Each data agent 142 may be configured to access data and/or metadatastored in the primary storage device(s) 104 associated with the dataagent 142 and process the data as appropriate. For example, during asecondary copy operation, the data agent 142 may arrange or assemble thedata and metadata into one or more files having a certain format (e.g.,a particular backup or archive format) before transferring the file(s)to a media agent 144 or other component. The file(s) may include a listof files or other metadata. Each data agent 142 can also assist inrestoring data or metadata to primary storage devices 104 from asecondary copy 116. For instance, the data agent 142 may operate inconjunction with the storage manager 140 and one or more of the mediaagents 144 to restore data from secondary storage device(s) 108.

Media Agents

As indicated above with respect to FIG. 1A, off-loading certainresponsibilities from the client computing devices 102 to intermediatecomponents such as the media agent(s) 144 can provide a number ofbenefits including improved client computing device 102 operation,faster secondary copy operation performance, and enhanced scalability.As one specific example which will be discussed below in further detail,the media agent 144 can act as a local cache of copied data and/ormetadata that it has stored to the secondary storage device(s) 108,providing improved restore capabilities.

Generally speaking, a media agent 144 may be implemented as a softwaremodule that manages, coordinates, and facilitates the transmission ofdata, as directed by the storage manager 140, between a client computingdevice 102 and one or more secondary storage devices 108. Whereas thestorage manager 140 controls the operation of the information managementsystem 100, the media agent 144 generally provides a portal to secondarystorage devices 108. For instance, other components in the systeminteract with the media agents 144 to gain access data stored on thesecondary storage devices 108, whether it be for the purposes ofreading, writing, modifying, or deleting data. Moreover, as will bedescribed further, media agents 144 can generate and store data andmetadata data that generally provides insight into the data stored onassociated secondary storage devices 108.

Media agents 144 can comprise separate nodes in the informationmanagement system 100 (e.g., nodes that are separate from the clientcomputing devices 102, storage manager 140, and/or secondary storagedevices 108). In general, a node within the information managementsystem 100 can be a logically and/or physically separate component, andin some cases is a component that is individually addressable orotherwise identifiable. In addition, each media agent 144 may reside ona dedicated secondary storage computing device 106 in some cases, whilein other embodiments a plurality of media agents 144 reside on the samesecondary storage computing device 106.

A media agent 144 (and corresponding media agent database 152) may beconsidered to be “associated with” a particular secondary storage device108 if that media agent 144 is capable of one or more of: routing and/orstoring data to the particular secondary storage device 108,coordinating the routing and/or storing of data to the particularsecondary storage device 108, retrieving data from the particularsecondary storage device 108, coordinating the retrieval of data from aparticular secondary storage device 108, and modifying and/or deletingdata retrieved from the particular secondary storage device 104.

While media agent(s) 144 are generally associated with one or moresecondary storage devices 108, one or more media agents 144 in certainembodiments are physically separate from the secondary storage devices108. For instance, the media agents 144 may reside on secondary storagecomputing devices 106 having different housings or packages than thesecondary storage devices 108. In one example, a media agent 144 resideson a first server computer and is in communication with a secondarystorage device(s) 108 residing in a separate, rack-mounted RAID-basedsystem.

Where the information management system 100 includes multiple mediaagents 144 (FIG. 1D), a first media agent 144 may provide failoverfunctionality for a second, failed media agent 144. In addition, mediaagents 144 can be dynamically selected for storage operations to provideload balancing. Failover and load balancing are described in greaterdetail below.

In operation, a media agent 144 associated with a particular secondarystorage device 108 may instruct the secondary storage device 108 toperform an information management operation. For instance, a media agent144 may instruct a tape library to use a robotic arm or other retrievalmeans to load or eject a certain storage media, and to subsequentlyarchive, migrate, or retrieve data to or from that media, e.g., for thepurpose of restoring the data to a client computing device 102. Asanother example, a secondary storage device 108 may include an array ofhard disk drives or solid state drives organized in a RAIDconfiguration, and the media agent 144 may forward a logical unit number(LUN) and other appropriate information to the array, which uses thereceived information to execute the desired storage operation. The mediaagent 144 may communicate with a secondary storage device 108 via asuitable communications link, such as a SCSI or Fiber Channel link.

As shown, each media agent 144 may maintain an associated media agentdatabase 152. The media agent database 152 may be stored in a disk orother storage device (not shown) that is local to the secondary storagecomputing device 106 on which the media agent 144 resides. In othercases, the media agent database 152 is stored remotely from thesecondary storage computing device 106.

The media agent database 152 can include, among other things, an index153 including data generated during secondary copy operations and otherstorage or information management operations. The index 153 provides amedia agent 144 or other component with a fast and efficient mechanismfor locating secondary copies 116 or other data stored in the secondarystorage devices 108. In some cases, the index 153 does not form a partof and is instead separate from the media agent database 152.

A media agent index 153 or other data structure associated with theparticular media agent 144 may include information about the storeddata. For instance, for each secondary copy 116, the index 153 mayinclude metadata such as a list of the data objects (e.g.,files/subdirectories, database objects, mailbox objects, etc.), a pathto the secondary copy 116 on the corresponding secondary storage device108, location information indicating where the data objects are storedin the secondary storage device 108, when the data objects were createdor modified, etc. Thus, the index 153 includes metadata associated withthe secondary copies 116 that is readily available for use in storageoperations and other activities without having to be first retrievedfrom the secondary storage device 108. In yet further embodiments, someor all of the data in the index 153 may instead or additionally bestored along with the data in a secondary storage device 108, e.g., witha copy of the index 153. In some embodiments, the secondary storagedevices 108 can include sufficient information to perform a “bare metalrestore”, where the operating system of a failed client computing device102 or other restore target is automatically rebuilt as part of arestore operation.

Because the index 153 maintained in the database 152 may operate as acache, it can also be referred to as an index cache. In such cases,information stored in the index cache 153 typically comprises data thatreflects certain particulars about storage operations that have occurredrelatively recently. After some triggering event, such as after acertain period of time elapses, or the index cache 153 reaches aparticular size, the index cache 153 may be copied or migrated to asecondary storage device(s) 108. This information may need to beretrieved and uploaded back into the index cache 153 or otherwiserestored to a media agent 144 to facilitate retrieval of data from thesecondary storage device(s) 108. In some embodiments, the cachedinformation may include format or containerization information relatedto archives or other files stored on the storage device(s) 108. In thismanner, the index cache 153 allows for accelerated restores.

In some alternative embodiments the media agent 144 generally acts as acoordinator or facilitator of storage operations between clientcomputing devices 102 and corresponding secondary storage devices 108,but does not actually write the data to the secondary storage device108. For instance, the storage manager 140 (or the media agent 144) mayinstruct a client computing device 102 and secondary storage device 108to communicate with one another directly. In such a case the clientcomputing device 102 transmits the data directly or via one or moreintermediary components to the secondary storage device 108 according tothe received instructions, and vice versa. In some such cases, the mediaagent 144 may still receive, process, and/or maintain metadata relatedto the storage operations. Moreover, in these embodiments, the payloaddata can flow through the media agent 144 for the purposes of populatingthe index cache 153 maintained in the media agent database 152, but notfor writing to the secondary storage device 108.

The media agent 144 and/or other components such as the storage manager140 may in some cases incorporate additional functionality, such as dataclassification, content indexing, deduplication, encryption,compression, and the like. Further details regarding these and otherfunctions are described below.

Distributed, Scalable Architecture

As described, certain functions of the information management system 100can be distributed amongst various physical and/or logical components inthe system. For instance, one or more of the storage manager 140, dataagents 142, and media agents 144 may reside on computing devices thatare physically separate from one another. This architecture can providea number of benefits.

For instance, hardware and software design choices for each distributedcomponent can be targeted to suit its particular function. The secondarycomputing devices 106 on which the media agents 144 reside can betailored for interaction with associated secondary storage devices 108and provide fast index cache operation, among other specific tasks.Similarly, the client computing device(s) 102 can be selected toeffectively service the applications 110 residing thereon, in order toefficiently produce and store primary data 112.

Moreover, in some cases, one or more of the individual components in theinformation management system 100 can be distributed to multiple,separate computing devices. As one example, for large file systems wherethe amount of data stored in the storage management database 146 isrelatively large, the management database 146 may be migrated to orotherwise reside on a specialized database server (e.g., an SQL server)separate from a server that implements the other functions of thestorage manager 140. This configuration can provide added protectionbecause the database 146 can be protected with standard databaseutilities (e.g., SQL log shipping or database replication) independentfrom other functions of the storage manager 140. The database 146 can beefficiently replicated to a remote site for use in the event of adisaster or other data loss incident at the primary site. Or thedatabase 146 can be replicated to another computing device within thesame site, such as to a higher performance machine in the event that astorage manager host device can no longer service the needs of a growinginformation management system 100.

The distributed architecture also provides both scalability andefficient component utilization. FIG. 1D shows an embodiment of theinformation management system 100 including a plurality of clientcomputing devices 102 and associated data agents 142 as well as aplurality of secondary storage computing devices 106 and associatedmedia agents 144.

Additional components can be added or subtracted based on the evolvingneeds of the information management system 100. For instance, dependingon where bottlenecks are identified, administrators can add additionalclient computing devices 102, secondary storage devices 106 (andcorresponding media agents 144), and/or secondary storage devices 108.Moreover, where multiple fungible components are available, loadbalancing can be implemented to dynamically address identifiedbottlenecks. As an example, the storage manager 140 may dynamicallyselect which media agents 144 and/or secondary storage devices 108 touse for storage operations based on a processing load analysis of themedia agents 144 and/or secondary storage devices 108, respectively.

Moreover, each client computing device 102 in some embodiments cancommunicate with, among other components, any of the media agents 144,e.g., as directed by the storage manager 140. And each media agent 144may be able to communicate with, among other components, any of thesecondary storage devices 108, e.g., as directed by the storage manager140. Thus, operations can be routed to the secondary storage devices 108in a dynamic and highly flexible manner, to provide load balancing,failover, and the like. Further examples of scalable systems capable ofdynamic storage operations, and of systems capable of performing loadbalancing and fail over are provided in U.S. Pat. No. 7,246,207, whichis incorporated by reference herein.

In alternative configurations, certain components are not distributedand may instead reside and execute on the same computing device. Forexample, in some embodiments one or more data agents 142 and the storagemanager 140 reside on the same client computing device 102. In anotherembodiment, one or more data agents 142 and one or more media agents 144reside on a single computing device.

Exemplary Types of Information Management Operations

In order to protect and leverage stored data, the information managementsystem 100 can be configured to perform a variety of informationmanagement operations. As will be described, these operations cangenerally include secondary copy and other data movement operations,processing and data manipulation operations, analysis, reporting, andmanagement operations.

Data Movement Operations

Data movement operations according to certain embodiments are generallyoperations that involve the copying or migration of data (e.g., payloaddata) between different locations in the information management system100 in an original/native and/or one or more different formats. Forexample, data movement operations can include operations in which storeddata is copied, migrated, or otherwise transferred from one or morefirst storage devices to one or more second storage devices, such asfrom primary storage device(s) 104 to secondary storage device(s) 108,from secondary storage device(s) 108 to different secondary storagedevice(s) 108, from secondary storage devices 108 to primary storagedevices 104, or from primary storage device(s) 104 to different primarystorage device(s) 104.

Data movement operations can include by way of example, backupoperations, archive operations, information lifecycle managementoperations such as hierarchical storage management operations,replication operations (e.g., continuous data replication operations),snapshot operations, deduplication or single-instancing operations,auxiliary copy operations, and the like. As will be discussed, some ofthese operations involve the copying, migration or other movement ofdata, without actually creating multiple, distinct copies. Nonetheless,some or all of these operations are referred to as “copy” operations forsimplicity.

Backup Operations

A backup operation creates a copy of a version of data (e.g., one ormore files or other data units) in primary data 112 at a particularpoint in time. Each subsequent backup copy may be maintainedindependently of the first. Further, a backup copy in some embodimentsis generally stored in a form that is different than the native format,e.g., a backup format. This can be in contrast to the version in primarydata 112 from which the backup copy is derived, and which may instead bestored in a native format of the source application(s) 110. In variouscases, backup copies can be stored in a format in which the data iscompressed, encrypted, deduplicated, and/or otherwise modified from theoriginal application format. For example, a backup copy may be stored ina backup format that facilitates compression and/or efficient long-termstorage.

Backup copies can have relatively long retention periods as compared toprimary data 112, and may be stored on media with slower retrieval timesthan primary data 112 and certain other types of secondary copies 116.On the other hand, backups may have relatively shorter retention periodsthan some other types of secondary copies 116, such as archive copies(described below). Backups may sometimes be stored at on offsitelocation.

Backup operations can include full, synthetic or incremental backups. Afull backup in some embodiments is generally a complete image of thedata to be protected. However, because full backup copies can consume arelatively large amount of storage, it can be useful to use a fullbackup copy as a baseline and only store changes relative to the fullbackup copy for subsequent backup copies.

For instance, a differential backup operation (or cumulative incrementalbackup operation) tracks and stores changes that have occurred since thelast full backup. Differential backups can grow quickly in size, but canprovide relatively efficient restore times because a restore can becompleted in some cases using only the full backup copy and the latestdifferential copy.

An incremental backup operation generally tracks and stores changessince the most recent backup copy of any type, which can greatly reducestorage utilization. In some cases, however, restore times can berelatively long in comparison to full or differential backups becausecompleting a restore operation may involve accessing a full backup inaddition to multiple incremental backups.

Any of the above types of backup operations can be at the volume-level,file-level, or block-level. Volume level backup operations generallyinvolve the copying of a data volume (e.g., a logical disk or partition)as a whole. In a file-level backup, the information management system100 may generally track changes to individual files at the file-level,and includes copies of files in the backup copy. In the case of ablock-level backup, files are broken into constituent blocks, andchanges are tracked at the block-level. Upon restore, the informationmanagement system 100 reassembles the blocks into files in a transparentfashion.

Far less data may actually be transferred and copied to the secondarystorage devices 108 during a file-level copy than a volume-level copy.Likewise, a block-level copy may involve the transfer of less data thana file-level copy, resulting in faster execution times. However,restoring a relatively higher-granularity copy can result in longerrestore times. For instance, when restoring a block-level copy, theprocess of locating constituent blocks can sometimes result in longerrestore times as compared to file-level backups. Similar to backupoperations, the other types of secondary copy operations describedherein can also be implemented at either the volume-level, file-level,or block-level.

Archive Operations

Because backup operations generally involve maintaining a version of thecopied data in primary data 112 and also maintaining backup copies insecondary storage device(s) 108, they can consume significant storagecapacity. To help reduce storage consumption, an archive operationaccording to certain embodiments creates a secondary copy 116 by bothcopying and removing source data. Or, seen another way, archiveoperations can involve moving some or all of the source data to thearchive destination. Thus, data satisfying criteria for removal (e.g.,data of a threshold age or size) from the source copy may be removedfrom source storage. Archive copies are sometimes stored in an archiveformat or other non-native application format. The source data may beprimary data 112 or a secondary copy 116, depending on the situation. Aswith backup copies, archive copies can be stored in a format in whichthe data is compressed, encrypted, deduplicated, and/or otherwisemodified from the original application format.

In addition, archive copies may be retained for relatively long periodsof time (e.g., years) and, in some cases, are never deleted. Archivecopies are generally retained for longer periods of time than backupcopies, for example. In certain embodiments, archive copies may be madeand kept for extended periods in order to meet compliance regulations.

Moreover, when primary data 112 is archived, in some cases the archivedprimary data 112 or a portion thereof is deleted when creating thearchive copy. Thus, archiving can serve the purpose of freeing up spacein the primary storage device(s) 104. Similarly, when a secondary copy116 is archived, the secondary copy 116 may be deleted, and an archivecopy can therefore serve the purpose of freeing up space in secondarystorage device(s) 108. In contrast, source copies often remain intactwhen creating backup copies. Examples of compatible data archivingoperations are provided in U.S. Pat. No. 7,107,298, entitled “SYSTEM ANDMETHOD FOR ARCHIVING OBJECTS IN AN INFORMATION STORE”, which isincorporated by reference herein.

Snapshot Operations

Snapshot operations can provide a relatively lightweight, efficientmechanism for protecting data. From an end-user viewpoint, a snapshotmay be thought of as an “instant” image of the primary data 112 at agiven point in time. In one embodiment, a snapshot may generally capturethe directory structure of an object in primary data 112 such as a fileor volume or other data set at a particular moment in time and may alsopreserve file attributes and contents. A snapshot in some cases iscreated relatively quickly, e.g., substantially instantly, using aminimum amount of file space, but may still function as a conventionalfile system backup.

A “hardware” snapshot operation can be a snapshot operation where atarget storage device (e.g., a primary storage device 104 or a secondarystorage device 108) performs the snapshot operation in a self-containedfashion, substantially independently, using hardware, firmware and/orsoftware residing on the storage device itself. For instance, thestorage device may be capable of performing snapshot operations uponrequest, generally without intervention or oversight from any of theother components in the information management system 100. In thismanner, using hardware snapshots can off-load processing involved increating and management from other components in the system 100.

A “software” snapshot operation, on the other hand, can be a snapshotoperation in which one or more other components in the system (e.g., theclient computing devices 102, media agents 104, etc.) implement asoftware layer that manages the snapshot operation via interaction withthe target storage device. For instance, the component implementing thesnapshot management software layer may derive a set of pointers and/ordata that represents the snapshot. The snapshot management softwarelayer may then transmit the same to the target storage device, alongwith appropriate instructions for writing the snapshot.

Some types of snapshots do not actually create another physical copy ofall the data as it existed at the particular point in time, but maysimply create pointers that are able to map files and directories tospecific memory locations (e.g., disk blocks) where the data resides, asit existed at the particular point in time. For example, a snapshot copymay include a set of pointers derived from the file system or anapplication. In some other cases, the snapshot may created at theblock-level, such as where creation of the snapshot occurs withoutawareness of the file system. Each pointer points to a respective storeddata block, so collectively, the set of pointers reflect the storagelocation and state of the data object (e.g., file(s) or volume(s) ordata set(s)) at a particular point in time when the snapshot copy wascreated.

In some embodiments, once a snapshot has been taken, subsequent changesto the file system typically do not overwrite the blocks in use at thetime of the snapshot. Therefore, the initial snapshot may use only asmall amount of disk space needed to record a mapping or other datastructure representing or otherwise tracking the blocks that correspondto the current state of the file system. Additional disk space isusually required only when files and directories are actually modifiedlater. Furthermore, when files are modified, typically only the pointerswhich map to blocks are copied, not the blocks themselves. In someembodiments, for example in the case of “copy-on-write” snapshots, whena block changes in primary storage, the block is copied to secondarystorage or cached in primary storage before the block is overwritten inprimary storage. The snapshot mapping of file system data is alsoupdated to reflect the changed block(s) at that particular point intime. In some other cases, a snapshot includes a full physical copy ofall or substantially all of the data represented by the snapshot.Further examples of snapshot operations are provided in U.S. Pat. No.7,529,782, which is incorporated by reference herein.

A snapshot copy in many cases can be made quickly and withoutsignificantly impacting primary computing resources because largeamounts of data need not be copied or moved. In some embodiments, asnapshot may exist as a virtual file system, parallel to the actual filesystem. Users in some cases gain read-only access to the record of filesand directories of the snapshot. By electing to restore primary data 112from a snapshot taken at a given point in time, users may also returnthe current file system to the state of the file system that existedwhen the snapshot was taken.

Replication Operations

Another type of secondary copy operation is a replication operation.Some types of secondary copies 116 are used to periodically captureimages of primary data 112 at particular points in time (e.g., backups,archives, and snapshots). However, it can also be useful for recoverypurposes to protect primary data 112 in a more continuous fashion, byreplicating the primary data 112 substantially as changes occur. In somecases a replication copy can be a mirror copy, for instance, wherechanges made to primary data 112 are mirrored or substantiallyimmediately copied to another location (e.g., to secondary storagedevice(s) 108). By copying each write operation to the replication copy,two storage systems are kept synchronized or substantially synchronizedso that they are virtually identical at approximately the same time.Where entire disk volumes are mirrored, however, mirroring can requiresignificant amount of storage space and utilizes a large amount ofprocessing resources.

According to some embodiments storage operations are performed onreplicated data that represents a recoverable state, or “known goodstate” of a particular application running on the source system. Forinstance, in certain embodiments, known good replication copies may beviewed as copies of primary data 112. This feature allows the system todirectly access, copy, restore, backup or otherwise manipulate thereplication copies as if the data was the “live”, primary data 112. Thiscan reduce access time, storage utilization, and impact on sourceapplications 110, among other benefits.

Based on known good state information, the information management system100 can replicate sections of application data that represent arecoverable state rather than rote copying of blocks of data. Examplesof compatible replication operations (e.g., continuous data replication)are provided in U.S. Pat. No. 7,617,262, which is incorporated byreference herein.

Deduplication/Single-Instancing Operations

Another type of data movement operation is deduplication orsingle-instance storage, which is useful to reduce the amount of datawithin the system. For instance, some or all of the above-describedsecondary storage operations can involve deduplication in some fashion.New data is read, broken down into portions (e.g., sub-file levelblocks, files, etc.) of a selected granularity, compared with blocksthat are already stored, and only the new blocks are stored. Blocks thatalready exist are represented as pointers to the already stored data.

In order to streamline the comparison process, the informationmanagement system 100 may calculate and/or store signatures (e.g.,hashes) corresponding to the individual data blocks in a database andcompare the hashes instead of comparing entire data blocks. In somecases, only a single instance of each element is stored, anddeduplication operations may therefore be referred to interchangeably as“single-instancing” operations. Depending on the implementation,however, deduplication or single-instancing operations can store morethan one instance of certain data blocks, but nonetheless significantlyreduce data redundancy.

Depending on the embodiment, deduplication blocks can be of fixed orvariable length. Using variable length blocks can provide enhanceddeduplication by responding to changes in the data stream, but caninvolve complex processing. In some cases, the information managementsystem 100 utilizes a technique for dynamically aligning deduplicationblocks (e.g., fixed-length blocks) based on changing content in the datastream, as described in U.S. Pat. Pub. No. 2012/0084269, which isincorporated by reference herein.

The information management system 100 can perform deduplication in avariety of manners at a variety of locations in the informationmanagement system 100. For instance, in some embodiments, theinformation management system 100 implements “target-side” deduplicationby deduplicating data (e.g., secondary copies 116) stored in thesecondary storage devices 108. In some such cases, the media agents 144are generally configured to manage the deduplication process. Forinstance, one or more of the media agents 144 maintain a correspondingdeduplication database that stores deduplication information (e.g.,datablock signatures). Examples of such a configuration are provided inU.S. Pat. Pub. No. 2012/0150826, which is incorporated by referenceherein. Instead of or in combination with “target-side” deduplication,deduplication can also be performed on the “source-side” (or“client-side”), e.g., to reduce the amount of traffic between the mediaagents 144 and the client computing device(s) 102 and/or reduceredundant data stored in the primary storage devices 104. Examples ofsuch deduplication techniques are provided in U.S. Pat. Pub. No.2012/0150818, which is incorporated by reference herein.

Information Lifecycle Management and Hierarchical Storage ManagementOperations

In some embodiments, files and other data over their lifetime move frommore expensive, quick access storage to less expensive, slower accessstorage. Operations associated with moving data through various tiers ofstorage are sometimes referred to as information lifecycle management(ILM) operations.

One type of ILM operation is a hierarchical storage management (HSM)operation. A HSM operation is generally an operation for automaticallymoving data between classes of storage devices, such as betweenhigh-cost and low-cost storage devices. For instance, an HSM operationmay involve movement of data from primary storage devices 104 tosecondary storage devices 108, or between tiers of secondary storagedevices 108. With each tier, the storage devices may be progressivelyrelatively cheaper, have relatively slower access/restore times, etc.For example, movement of data between tiers may occur as data becomesless important over time.

In some embodiments, an HSM operation is similar to an archive operationin that creating an HSM copy may (though not always) involve deletingsome of the source data, e.g., according to one or more criteria relatedto the source data. For example, an HSM copy may include data fromprimary data 112 or a secondary copy 116 that is larger than a givensize threshold or older than a given age threshold and that is stored ina backup format.

Often, and unlike some types of archive copies, HSM data that is removedor aged from the source copy is replaced by a logical reference pointeror stub. The reference pointer or stub can be stored in the primarystorage device 104 (or other source storage device, such as a secondarystorage device 108) to replace the deleted data in primary data 112 (orother source copy) and to point to or otherwise indicate the newlocation in a secondary storage device 108.

According to one example, files are generally moved between higher andlower cost storage depending on how often the files are accessed. When auser requests access to the HSM data that has been removed or migrated,the information management system 100 uses the stub to locate the dataand often make recovery of the data appear transparent, even though theHSM data may be stored at a location different from the remaining sourcedata. In this manner, the data appears to the user (e.g., in file systembrowsing windows and the like) as if it still resides in the sourcelocation (e.g., in a primary storage device 104). The stub may alsoinclude some metadata associated with the corresponding data, so that afile system and/or application can provide some information about thedata object and/or a limited-functionality version (e.g., a preview) ofthe data object.

An HSM copy may be stored in a format other than the native applicationformat (e.g., where the data is compressed, encrypted, deduplicated,and/or otherwise modified from the original application format). In somecases, copies which involve the removal of data from source storage andthe maintenance of stub or other logical reference information on sourcestorage may be referred to generally as “on-line archive copies”. On theother hand, copies which involve the removal of data from source storagewithout the maintenance of stub or other logical reference informationon source storage may be referred to as “off-line archive copies”.Examples of HSM and ILM techniques are provided in U.S. Pat. No.7,343,453, which is incorporated by reference herein.

Auxiliary Copy and Disaster Recovery Operations

An auxiliary copy is generally a copy operation in which a copy iscreated of an existing secondary copy 116. For instance, an initial or“primary” secondary copy 116 may be generated using or otherwise bederived from primary data 112 (or other data residing in the secondarystorage subsystem 118), whereas an auxiliary copy is generated from theinitial secondary copy 116. Auxiliary copies can be used to createadditional standby copies of data and may reside on different secondarystorage devices 108 than initial secondary copies 116. Thus, auxiliarycopies can be used for recovery purposes if initial secondary copies 116become unavailable. Exemplary compatible auxiliary copy techniques aredescribed in further detail in U.S. Pat. No. 8,230,195, which isincorporated by reference herein.

The information management system 100 may also perform disaster recoveryoperations that make or retain disaster recovery copies, often assecondary, high-availability disk copies. The information managementsystem 100 may create secondary disk copies and store the copies atdisaster recovery locations using auxiliary copy or replicationoperations, such as continuous data replication technologies. Dependingon the particular data protection goals, disaster recovery locations canbe remote from the client computing devices 102 and primary storagedevices 104, remote from some or all of the secondary storage devices108, or both.

Data Analysis, Reporting, and Management Operations

Data analysis, reporting, and management operations can be differentthan data movement operations in that they do not necessarily involvethe copying, migration, or other transfer of data (e.g., primary data112 or secondary copies 116) between different locations in the system.For instance, data analysis operations may involve processing (e.g.,offline processing) or modification of already stored primary data 112and/or secondary copies 116. However, in some embodiments data analysisoperations are performed in conjunction with data movement operations.Some data analysis operations include content indexing operations andclassification operations which can be useful in leveraging the dataunder management to provide enhanced search and other features. Otherdata analysis operations such as compression and encryption can providedata reduction and security benefits, respectively.

Classification Operations/Content Indexing

In some embodiments, the information management system 100 analyzes andindexes characteristics, content, and metadata associated with the datastored within the primary data 112 and/or secondary copies 116,providing enhanced search capabilities for data discovery and otherpurposes. The content indexing can be used to identify files or otherdata objects having pre-defined content (e.g., user-defined keywords orphrases), metadata (e.g., email metadata such as “to”, “from”, “cc”,“bcc”, attachment name, received time, etc.).

The information management system 100 generally organizes and cataloguesthe results in a content index, which may be stored within the mediaagent database 152, for example. The content index can also include thestorage locations of (or pointer references to) the indexed data in theprimary data 112 or secondary copies 116, as appropriate. The resultsmay also be stored, in the form of a content index database orotherwise, elsewhere in the information management system 100 (e.g., inthe primary storage devices 104, or in the secondary storage device108). Such index data provides the storage manager 140 or anothercomponent with an efficient mechanism for locating primary data 112and/or secondary copies 116 of data objects that match particularcriteria.

For instance, search criteria can be specified by a user through userinterface 158 of the storage manager 140. In some cases, the informationmanagement system 100 analyzes data and/or metadata in secondary copies116 to create an “off-line” content index, without significantlyimpacting the performance of the client computing devices 102. Dependingon the embodiment, the system can also implement “on-line” contentindexing, e.g., of primary data 112. Examples of compatible contentindexing techniques are provided in U.S. Pat. No. 8,170,995, which isincorporated by reference herein.

In order to leverage the data stored in the information managementsystem 100 to perform these and other tasks, one or more components canbe configured to scan data and/or associated metadata for classificationpurposes to populate a database of information (which can be referred toas a “metabase”). Such scanned, classified data and/or metadata may beincluded in a separate database and/or on a separate storage device fromprimary data 112 (and/or secondary copies 116), such that operationsrelated to the database do not significantly impact performance on othercomponents in the information management system 100.

In other cases, the database(s) may be stored along with primary data112 and/or secondary copies 116. Files or other data objects can beassociated with user-specified identifiers (e.g., tag entries) in themedia agent 144 (or other indices) to facilitate searches of stored dataobjects. Among a number of other benefits, the metabase can also allowefficient, automatic identification of files or other data objects toassociate with secondary copy or other information management operations(e.g., in lieu of scanning an entire file system). Examples ofcompatible metabases and data classification operations are provided inU.S. Pat. Nos. 8,229,954 and 7,747,579, which are incorporated byreference herein.

Encryption Operations

The information management system 100 in some cases is configured toprocess data (e.g., files or other data objects, secondary copies 116,etc.), according to an appropriate encryption algorithm (e.g., Blowfish,Advanced Encryption Standard [AES], Triple Data Encryption Standard[3-DES], etc.) to limit access and provide data security in theinformation management system 100.

The information management system 100 in some cases encrypts the data atthe client level, such that the client computing devices 102 (e.g., thedata agents 142) encrypt the data prior to forwarding the data to othercomponents, e.g., before sending the data media agents 144 during asecondary copy operation. In such cases, the client computing device 102may maintain or have access to an encryption key or passphrase fordecrypting the data upon restore. Encryption can also occur whencreating copies of secondary copies, e.g., when creating auxiliarycopies or archive copies. In yet further embodiments, the secondarystorage devices 108 can implement built-in, high performance hardwareencryption.

Management and Reporting Operations

Certain embodiments leverage the integrated, ubiquitous nature of theinformation management system 100 to provide useful system-widemanagement and reporting functions. Examples of some compatiblemanagement and reporting techniques are provided in U.S. Pat. No.7,343,453, entitled “HIERARCHICAL SYSTEMS AND METHODS FOR PROVIDING AUNIFIED VIEW OF STORAGE INFORMATION”, which is incorporated by referenceherein.

Operations management can generally include monitoring and managing thehealth and performance of information management system 100 by, withoutlimitation, performing error tracking, generating granularstorage/performance metrics (e.g., job success/failure information,deduplication efficiency, etc.), generating storage modeling and costinginformation, and the like.

As an example, a storage manager 140 or other component in theinformation management system 100 may analyze traffic patterns andsuggest or automatically route data via a particular route to e.g.,certain facilitate storage and minimize congestion. In some embodiments,the system can generate predictions relating to storage operations orstorage operation information. Such predictions described may be basedon a trending analysis that may be used to predict various networkoperations or use of network resources such as network traffic levels,storage media use, use of bandwidth of communication links, use of mediaagent components, etc. Further examples of traffic analysis, trendanalysis, prediction generation, and the like are described in U.S. Pat.No. 7,343,453, which is incorporated by reference herein.

In some configurations, a master storage manager 140 may track thestatus of a set of associated storage operation cells in a hierarchy ofinformation management cells, such as the status of jobs, systemcomponents, system resources, and other items, by communicating withstorage managers 140 (or other components) in the respective storageoperation cells. Moreover, the master storage manager 140 may track thestatus of its associated storage operation cells and associatedinformation management operations by receiving periodic status updatesfrom the storage managers 140 (or other components) in the respectivecells regarding jobs, system components, system resources, and otheritems. In some embodiments, a master storage manager 140 may storestatus information and other information regarding its associatedstorage operation cells and other system information in its index 150(or other location).

The master storage manager or other component in the system may alsodetermine whether a storage-related criteria or other criteria issatisfied, and perform an action or trigger event (e.g., data migration)in response to the criteria being satisfied, such as where a storagethreshold is met for a particular volume, or where inadequate protectionexists for certain data. For instance, in some embodiments, the systemuses data from one or more storage operation cells to advise users ofrisks or indicates actions that can be used to mitigate or otherwiseminimize these risks, and in some embodiments, dynamically takes actionto mitigate or minimize these risks. For example, an informationmanagement policy may specify certain requirements (e.g., that a storagedevice should maintain a certain amount of free space, that secondarycopies should occur at a particular interval, that data should be agedand migrated to other storage after a particular period, that data on asecondary volume should always have a certain level of availability andbe able to be restored within a given time period, that data on asecondary volume may be mirrored or otherwise migrated to a specifiednumber of other volumes, etc.). If a risk condition or other criteria istriggered, the system can notify the user of these conditions and maysuggest (or automatically implement) an action to mitigate or otherwiseaddress the condition or minimize risk. For example, the system mayindicate that data from a primary copy 112 should be migrated to asecondary storage device 108 to free space on the primary storage device104. Examples of the use of risk factors and other triggering criteriaare described in U.S. Pat. No. 7,343,453, which is incorporated byreference herein.

In some embodiments, the system 100 may also determine whether a metricor other indication satisfies a particular storage criteria and, if so,perform an action. For example, as previously described, a storagepolicy or other definition might indicate that a storage manager 140should initiate a particular action if a storage metric or otherindication drops below or otherwise fails to satisfy a specifiedcriteria such as a threshold of data protection. Examples of suchmetrics are described in U.S. Pat. No. 7,343,453, which is incorporatedby reference herein.

In some embodiments, risk factors may be quantified into certainmeasurable service or risk levels for ease of comprehension. Forexample, certain applications and associated data may be considered tobe more important by an enterprise than other data and services.Financial compliance data, for example, may be of greater importancethan marketing materials, etc. Network administrators may assignpriorities or “weights” to certain data or applications, correspondingto its importance (priority value). The level of compliance with thestorage operations specified for these applications may also be assigneda certain value. Thus, the health, impact and overall importance of aservice on an enterprise may be determined, for example, by measuringthe compliance value and calculating the product of the priority valueand the compliance value to determine the “service level” and comparingit to certain operational thresholds to determine if the operation isbeing performed within a specified data protection service level.Further examples of the service level determination are provided in U.S.Pat. No. 7,343,453, which is incorporated by reference herein.

The system 100 may additionally calculate data costing and dataavailability associated with information management operation cellsaccording to an embodiment of the invention. For instance, data receivedfrom the cell may be used in conjunction with hardware-relatedinformation and other information about network elements to generateindications of costs associated with storage of particular data in thesystem or the availability of particular data in the system. In general,components in the system are identified and associated information isobtained (dynamically or manually). Characteristics or metricsassociated with the network elements may be identified and associatedwith that component element for further use generating an indication ofstorage cost or data availability. Exemplary information generated couldinclude how fast a particular department is using up available storagespace, how long data would take to recover over a particular networkpathway from a particular secondary storage device, costs over time,etc. Moreover, in some embodiments, such information may be used todetermine or predict the overall cost associated with the storage ofcertain information. The cost associated with hosting a certainapplication may be based, at least in part, on the type of media onwhich the data resides. Storage devices may be assigned to a particularcost category which is indicative of the cost of storing information onthat device. Further examples of costing techniques are described inU.S. Pat. No. 7,343,453, which is incorporated by reference herein.

Any of the above types of information (e.g., information related totrending, predictions, job, cell or component status, risk, servicelevel, costing, etc.) can generally be provided to users via the userinterface 158 in a single, integrated view or console. The console maysupport a reporting capability that allows for the generation of avariety of reports, which may be tailored to a particular aspect ofinformation management. Report types may include: scheduling, eventmanagement, media management and data aging. Available reports may alsoinclude backup history, data aging history, auxiliary copy history, jobhistory, library and drive, media in library, restore history andstorage policy. Such reports may be specified and created at a certainpoint in time as a network analysis, forecasting, or provisioning tool.Integrated reports may also be generated that illustrate storage andperformance metrics, risks and storage costing information. Moreover,users may create their own reports based on specific needs.

The integrated user interface 158 can include an option to show a“virtual view” of the system that graphically depicts the variouscomponents in the system using appropriate icons. As one example, theuser interface may provide a graphical depiction of one or more primarystorage devices 104, the secondary storage devices 108, data agents 142and/or media agents 144, and their relationship to one another in theinformation management system 100. The operations managementfunctionality can facilitate planning and decision-making. For example,in some embodiments, a user may view the status of some or all jobs aswell as the status of each component of the information managementsystem 100. Users may then plan and make decisions based on this data.For instance, a user may view high-level information regarding storageoperations for the information management system 100, such as jobstatus, component status, resource status (e.g., network pathways,etc.), and other information. The user may also drill down or use othermeans to obtain more detailed information regarding a particularcomponent, job, or the like.

Further examples of some reporting techniques and associated interfacesproviding an integrated view of an information management system areprovided in U.S. Pat. No. 7,343,453, which is incorporated by referenceherein.

The information management system 100 can also be configured to performsystem-wide e-discovery operations in some embodiments. In general,e-discovery operations provide a unified collection and searchcapability for data in the system, such as data stored in the secondarystorage devices 108 (e.g., backups, archives, or other secondary copies116). For example, the information management system 100 may constructand maintain a virtual repository for data stored in the informationmanagement system 100 that is integrated across source applications 110,different storage device types, etc. According to some embodiments,e-discovery utilizes other techniques described herein, such as dataclassification and/or content indexing.

Information Management Policies

As indicated previously, an information management policy 148 caninclude a data structure or other information source that specifies aset of parameters (e.g., criteria and rules) associated with secondarycopy or other information management operations.

One type of information management policy 148 is a storage policy.According to certain embodiments, a storage policy generally comprises adata structure or other information source that defines (or includesinformation sufficient to determine) a set of preferences or othercriteria for performing information management operations. Storagepolicies can include one or more of the following items: (1) what datawill be associated with the storage policy; (2) a destination to whichthe data will be stored; (3) datapath information specifying how thedata will be communicated to the destination; (4) the type of storageoperation to be performed; and (5) retention information specifying howlong the data will be retained at the destination.

As an illustrative example, data associated with a storage policy can belogically organized into groups. In some cases, these logical groupingscan be referred to as “sub-clients”. A sub-client may represent staticor dynamic associations of portions of a data volume. Sub-clients mayrepresent mutually exclusive portions. Thus, in certain embodiments, aportion of data may be given a label and the association is stored as astatic entity in an index, database or other storage location.

Sub-clients may also be used as an effective administrative scheme oforganizing data according to data type, department within theenterprise, storage preferences, or the like. Depending on theconfiguration, sub-clients can correspond to files, folders, virtualmachines, databases, etc. In one exemplary scenario, an administratormay find it preferable to separate e-mail data from financial data usingtwo different sub-clients.

A storage policy can define where data is stored by specifying a targetor destination storage device (or group of storage devices). Forinstance, where the secondary storage device 108 includes a group ofdisk libraries, the storage policy may specify a particular disk libraryfor storing the sub-clients associated with the policy. As anotherexample, where the secondary storage devices 108 include one or moretape libraries, the storage policy may specify a particular tape libraryfor storing the sub-clients associated with the storage policy, and mayalso specify a drive pool and a tape pool defining a group of tapedrives and a group of tapes, respectively, for use in storing thesub-client data. While information in the storage policy can bestatically assigned in some cases, some or all of the information in thestorage policy can also be dynamically determined based on criteria,which can be set forth in the storage policy. For instance, based onsuch criteria, a particular destination storage device(s) (or otherparameter of the storage policy) may be determined based oncharacteristics associated with the data involved in a particularstorage operation, device availability (e.g., availability of asecondary storage device 108 or a media agent 144), network status andconditions (e.g., identified bottlenecks), user credentials, and thelike)

Datapath information can also be included in the storage policy. Forinstance, the storage policy may specify network pathways and componentsto utilize when moving the data to the destination storage device(s). Insome embodiments, the storage policy specifies one or more media agents144 for conveying data (e.g., one or more sub-clients) associated withthe storage policy between the source (e.g., one or more host clientcomputing devices 102) and destination (e.g., a particular targetsecondary storage device 108).

A storage policy can also specify the type(s) of operations associatedwith the storage policy, such as a backup, archive, snapshot, auxiliarycopy, or the like. Retention information can specify how long the datawill be kept, depending on organizational needs (e.g., a number of days,months, years, etc.)

The information management policies 148 may also include one or morescheduling policies specifying when and how often to perform operations.Scheduling information may specify with what frequency (e.g., hourly,weekly, daily, event-based, etc.) or under what triggering conditionssecondary copy or other information management operations will takeplace. Scheduling policies in some cases are associated with particularcomponents, such as particular logical groupings of data associated witha storage policy (e.g., a sub-client), client computing device 102, andthe like. In one configuration, a separate scheduling policy ismaintained for particular logical groupings of data on a clientcomputing device 102. The scheduling policy specifies that those logicalgroupings are to be moved to secondary storage devices 108 every houraccording to storage policies associated with the respectivesub-clients.

When adding a new client computing device 102, administrators canmanually configure information management policies 148 and/or othersettings, e.g., via the user interface 158. However, this can be aninvolved process resulting in delays, and it may be desirable to begindata protecting operations quickly.

Thus, in some embodiments, the information management system 100automatically applies a default configuration to client computing device102. As one example, when one or more data agent(s) 142 are installed onone or more client computing devices 102, the installation script mayregister the client computing device 102 with the storage manager 140,which in turn applies the default configuration to the new clientcomputing device 102. In this manner, data protection operations canbegin substantially immediately. The default configuration can include adefault storage policy, for example, and can specify any appropriateinformation sufficient to begin data protection operations. This caninclude a type of data protection operation, scheduling information, atarget secondary storage device 108, data path information (e.g., aparticular media agent 144), and the like.

Other types of information management policies 148 are possible. Forinstance, the information management policies 148 can also include oneor more audit or security policies. An audit policy is a set ofpreferences, rules and/or criteria that protect sensitive data in theinformation management system 100. For example, an audit policy maydefine “sensitive objects” as files or objects that contain particularkeywords (e.g. “confidential,” or “privileged”) and/or are associatedwith particular keywords (e.g., in metadata) or particular flags (e.g.,in metadata identifying a document or email as personal, confidential,etc.).

An audit policy may further specify rules for handling sensitiveobjects. As an example, an audit policy may require that a reviewerapprove the transfer of any sensitive objects to a cloud storage site,and that if approval is denied for a particular sensitive object, thesensitive object should be transferred to a local storage device 104instead. To facilitate this approval, the audit policy may furtherspecify how a secondary storage computing device 106 or other systemcomponent should notify a reviewer that a sensitive object is slated fortransfer.

In some implementations, the information management policies 148 mayinclude one or more provisioning policies. A provisioning policy caninclude a set of preferences, priorities, rules, and/or criteria thatspecify how clients 102 (or groups thereof) may utilize systemresources, such as available storage on cloud storage and/or networkbandwidth. A provisioning policy specifies, for example, data quotas forparticular client computing devices 102 (e.g. a number of gigabytes thatcan be stored monthly, quarterly or annually). The storage manager 140or other components may enforce the provisioning policy. For instance,the media agents 144 may enforce the policy when transferring data tosecondary storage devices 108. If a client computing device 102 exceedsa quota, a budget for the client computing device 102 (or associateddepartment) is adjusted accordingly or an alert may trigger.

While the above types of information management policies 148 have beendescribed as separate policies, one or more of these can be generallycombined into a single information management policy 148. For instance,a storage policy may also include or otherwise be associated with one ormore scheduling, audit, or provisioning policies. Moreover, whilestorage policies are typically associated with moving and storing data,other policies may be associated with other types of informationmanagement operations. The following is a non-exhaustive list of itemsthe information management policies 148 may specify:

-   -   schedules or other timing information, e.g., specifying when        and/or how often to perform information management operations;    -   the type of copy 116 (e.g., type of secondary copy) and/or copy        (e.g., type of secondary copy) format (e.g., snapshot, backup,        archive, HSM, etc.);    -   a location or a class or quality of storage for storing        secondary copies 116 (e.g., one or more particular secondary        storage devices 108);    -   preferences regarding whether and how to encrypt, compress,        deduplicate, or otherwise modify or transform secondary copies        116;    -   which system components and/or network pathways (e.g., preferred        media agents 144) should be used to perform secondary storage        operations;    -   resource allocation between different computing devices or other        system components used in performing information management        operations (e.g., bandwidth allocation, available storage        capacity, etc.);    -   whether and how to synchronize or otherwise distribute files or        other data objects across multiple computing devices or hosted        services; and    -   retention information specifying the length of time primary data        112 and/or secondary copies 116 should be retained, e.g., in a        particular class or tier of storage devices, or within the        information management system 100.

Policies can additionally specify or depend on a variety of historicalor current criteria that may be used to determine which rules to applyto a particular data object, system component, or information managementoperation, such as:

-   -   frequency with which primary data 112 or a secondary copy 116 of        a data object or metadata has been or is predicted to be used,        accessed, or modified;    -   time-related factors (e.g., aging information such as time since        the creation or modification of a data object);    -   deduplication information (e.g., hashes, data blocks,        deduplication block size, deduplication efficiency or other        metrics);    -   an estimated or historic usage or cost associated with different        components (e.g., with secondary storage devices 108);    -   the identity of users, applications 110, client computing        devices 102 and/or other computing devices that created,        accessed, modified, or otherwise utilized primary data 112 or        secondary copies 116;    -   a relative sensitivity (e.g., confidentiality) of a data object,        e.g., as determined by its content and/or metadata;    -   the current or historical storage capacity of various storage        devices;    -   the current or historical network capacity of network pathways        connecting various components within the storage operation cell;    -   access control lists or other security information; and    -   the content of a particular data object (e.g., its textual        content) or of metadata associated with the data object.

Exemplary Storage Policy and Secondary Storage Operations

FIG. 1E shows a data flow data diagram depicting performance of storageoperations by an embodiment of an information management system 100,according to an exemplary data storage policy 148A. The informationmanagement system 100 includes a storage manger 140, a client computingdevice 102 having a file system data agent 142A and an email data agent142B residing thereon, a primary storage device 104, two media agents144A, 144B, and two secondary storage devices 108A, 108B: a disk library108A and a tape library 108B. As shown, the primary storage device 104includes primary data 112A, 112B associated with a logical grouping ofdata associated with a file system) and a logical grouping of dataassociated with email data, respectively. Although for simplicity thelogical grouping of data associated with the file system is referred toas a file system sub-client, and the logical grouping of data associatedwith the email data is referred to as an email sub-client, thetechniques described with respect to FIG. 1E can be utilized inconjunction with data that is organized in a variety of other manners.

As indicated by the dashed box, the second media agent 144B and the tapelibrary 108B are “off-site”, and may therefore be remotely located fromthe other components in the information management system 100 (e.g., ina different city, office building, etc.). In this manner, informationstored on the tape library 108B may provide protection in the event of adisaster or other failure.

The file system sub-client and its associated primary data 112A incertain embodiments generally comprise information generated by the filesystem and/or operating system of the client computing device 102, andcan include, for example, file system data (e.g., regular files, filetables, mount points, etc.), operating system data (e.g., registries,event logs, etc.), and the like. The e-mail sub-client, on the otherhand, and its associated primary data 112B, include data generated by ane-mail client application operating on the client computing device 102,and can include mailbox information, folder information, emails,attachments, associated database information, and the like. As describedabove, the sub-clients can be logical containers, and the data includedin the corresponding primary data 112A, 112B may or may not be storedcontiguously.

The exemplary storage policy 148A includes backup copy preferences orrule set 160, disaster recovery copy preferences rule set 162, andcompliance copy preferences or rule set 164. The backup copy rule set160 specifies that it is associated with a file system sub-client 166and an email sub-client 168. Each of these sub-clients 166, 168 areassociated with the particular client computing device 102. The backupcopy rule set 160 further specifies that the backup operation will bewritten to the disk library 108A, and designates a particular mediaagent 144A to convey the data to the disk library 108A. Finally, thebackup copy rule set 160 specifies that backup copies created accordingto the rule set 160 are scheduled to be generated on an hourly basis andto be retained for 30 days. In some other embodiments, schedulinginformation is not included in the storage policy 148A, and is insteadspecified by a separate scheduling policy.

The disaster recovery copy rule set 162 is associated with the same twosub-clients 166, 168. However, the disaster recovery copy rule set 162is associated with the tape library 108B, unlike the backup copy ruleset 160. Moreover, the disaster recovery copy rule set 162 specifiesthat a different media agent 144B than the media agent 144A associatedwith the backup copy rule set 160 will be used to convey the data to thetape library 108B. As indicated, disaster recovery copies createdaccording to the rule set 162 will be retained for 60 days, and will begenerated on a daily basis. Disaster recovery copies generated accordingto the disaster recovery copy rule set 162 can provide protection in theevent of a disaster or other data-loss event that would affect thebackup copy 116A maintained on the disk library 108A.

The compliance copy rule set 164 is only associated with the emailsub-client 166, and not the file system sub-client 168. Compliancecopies generated according to the compliance copy rule set 164 willtherefore not include primary data 112A from the file system sub-client166. For instance, the organization may be under an obligation to storemaintain copies of email data for a particular period of time (e.g., 10years) to comply with state or federal regulations, while similarregulations do not apply to the file system data. The compliance copyrule set 164 is associated with the same tape library 108B and mediaagent 144B as the disaster recovery copy rule set 162, although adifferent storage device or media agent could be used in otherembodiments. Finally, the compliance copy rule set 164 specifies thatcopies generated under the compliance copy rule set 164 will be retainedfor 10 years, and will be generated on a quarterly basis.

At step 1, the storage manager 140 initiates a backup operationaccording to the backup copy rule set 160. For instance, a schedulingservice running on the storage manager 140 accesses schedulinginformation from the backup copy rule set 160 or a separate schedulingpolicy associated with the client computing device 102, and initiates abackup copy operation on an hourly basis. Thus, at the scheduled timeslot the storage manager 140 sends instructions to the client computingdevice 102 to begin the backup operation.

At step 2, the file system data agent 142A and the email data agent 142Bresiding on the client computing device 102 respond to the instructionsreceived from the storage manager 140 by accessing and processing theprimary data 112A, 112B involved in the copy operation from the primarystorage device 104. Because the operation is a backup copy operation,the data agent(s) 142A, 142B may format the data into a backup format orotherwise process the data.

At step 3, the client computing device 102 communicates the retrieved,processed data to the first media agent 144A, as directed by the storagemanager 140, according to the backup copy rule set 160. In some otherembodiments, the information management system 100 may implement aload-balancing, availability-based, or other appropriate algorithm toselect from the available set of media agents 144A, 144B. Regardless ofthe manner the media agent 144A is selected, the storage manager 140 mayfurther keep a record in the storage manager database 140 of theassociation between the selected media agent 144A and the clientcomputing device 102 and/or between the selected media agent 144A andthe backup copy 116A.

The target media agent 144A receives the data from the client computingdevice 102, and at step 4 conveys the data to the disk library 108A tocreate the backup copy 116A, again at the direction of the storagemanager 140 and according to the backup copy rule set 160. The secondarystorage device 108A can be selected in other ways. For instance, themedia agent 144A may have a dedicated association with a particularsecondary storage device(s), or the storage manager 140 or media agent144A may select from a plurality of secondary storage devices, e.g.,according to availability, using one of the techniques described in U.S.Pat. No. 7,246,207, which is incorporated by reference herein.

The media agent 144A can also update its index 153 to include dataand/or metadata related to the backup copy 116A, such as informationindicating where the backup copy 116A resides on the disk library 108A,data and metadata for cache retrieval, etc. After the 30 day retentionperiod expires, the storage manager 140 instructs the media agent 144Ato delete the backup copy 116A from the disk library 108A. The storagemanager 140 may similarly update its index 150 to include informationrelating to the storage operation, such as information relating to thetype of storage operation, a physical location associated with one ormore copies created by the storage operation, the time the storageoperation was performed, status information relating to the storageoperation, the components involved in the storage operation, and thelike. In some cases, the storage manager 140 may update its index 150 toinclude some or all of the information stored in the index 153 of themedia agent 144A.

At step 5, the storage manager 140 initiates the creation of a disasterrecovery copy 1168 according to the disaster recovery copy rule set 162.For instance, at step 6, based on instructions received from the storagemanager 140 at step 5, the specified media agent 144B retrieves the mostrecent backup copy 116A from the disk library 108A.

At step 7, again at the direction of the storage manager 140 and asspecified in the disaster recovery copy rule set 162, the media agent144B uses the retrieved data to create a disaster recovery copy 1168 onthe tape library 108B. In some cases, the disaster recovery copy 1168 isa direct, mirror copy of the backup copy 116A, and remains in the backupformat. In other embodiments, the disaster recovery copy 116C may begenerated in some other manner, such as by using the primary data 112A,112B from the storage device 104 as source data. The disaster recoverycopy operation is initiated once a day and the disaster recovery copies116A are deleted after 60 days.

At step 8, the storage manager 140 initiates the creation of acompliance copy 116C, according to the compliance copy rule set 164. Forinstance, the storage manager 140 instructs the media agent 144B tocreate the compliance copy 116C on the tape library 108B at step 9, asspecified in the compliance copy rule set 164. In the example, thecompliance copy 116C is generated using the disaster recovery copy 1168.In other embodiments, the compliance copy 116C is instead generatedusing either the primary data 112B corresponding to the email sub-clientor using the backup copy 116A from the disk library 108A as source data.As specified, in the illustrated example, compliance copies 116C arecreated quarterly, and are deleted after ten years.

While not shown in FIG. 1E, at some later point in time, a restoreoperation can be initiated involving one or more of the secondary copies116A, 1168, 116C. As one example, a user may manually initiate a restoreof the backup copy 116A by interacting with the user interface 158 ofthe storage manager 140. The storage manager 140 then accesses data inits index 150 (and/or the respective storage policy 148A) associatedwith the selected backup copy 116A to identify the appropriate mediaagent 144A and/or secondary storage device 116A.

In other cases, a media agent may be selected for use in the restoreoperation based on a load balancing algorithm, an availability basedalgorithm, or other criteria. The selected media agent 144A retrievesthe data from the disk library 108A. For instance, the media agent 144Amay access its index 153 to identify a location of the backup copy 116Aon the disk library 108A, or may access location information residing onthe disk 108A itself.

When the backup copy 116A was recently created or accessed, the mediaagent 144A accesses a cached version of the backup copy 116A residing inthe media agent index 153, without having to access the disk library108A for some or all of the data. Once it has retrieved the backup copy116A, the media agent 144A communicates the data to the source clientcomputing device 102. Upon receipt, the file system data agent 142A andthe email data agent 142B may unpackage (e.g., restore from a backupformat to the native application format) the data in the backup copy116A and restore the unpackaged data to the primary storage device 104.

Exemplary Secondary Copy Formatting

The formatting and structure of secondary copies 116 can vary, dependingon the embodiment. In some cases, secondary copies 116 are formatted asa series of logical data units or “chunks” (e.g., 512 MB, 1 GB, 2 GB, 4GB, or 8 GB chunks). This can facilitate efficient communication andwriting to secondary storage devices 108, e.g., according to resourceavailability. For example, a single secondary copy 116 may be written ona chunk-by-chunk basis to a single secondary storage device 108 oracross multiple secondary storage devices 108. In some cases, users canselect different chunk sizes, e.g., to improve throughput to tapestorage devices.

Generally, each chunk can include a header and a payload. The payloadcan include files (or other data units) or subsets thereof included inthe chunk, whereas the chunk header generally includes metadata relatingto the chunk, some or all of which may be derived from the payload. Forexample, during a secondary copy operation, the media agent 144, storagemanager 140, or other component may divide the associated files intochunks and generate headers for each chunk by processing the constituentfiles.

The headers can include a variety of information such as fileidentifier(s), volume(s), offset(s), or other information associatedwith the payload data items, a chunk sequence number, etc. Importantly,in addition to being stored with the secondary copy 116 on the secondarystorage device 108, the chunk headers can also be stored to the index153 of the associated media agent(s) 144 and/or the storage managerindex 150. This is useful in some cases for providing faster processingof secondary copies 116 during restores or other operations. In somecases, once a chunk is successfully transferred to a secondary storagedevice 108, the secondary storage device 108 returns an indication ofreceipt, e.g., to the media agent 144 and/or storage manager 140, whichmay update their respective indexes 150, 153 accordingly. Duringrestore, chunks may be processed (e.g., by the media agent 144)according to the information in the chunk header to reassemble thefiles.

Data can also be communicated within the information management system100 in data channels that connect the client computing devices 102 tothe secondary storage devices 108. These data channels can be referredto as “data streams”, and multiple data streams can be employed toparallelize an information management operation, improving data transferrate, among providing other advantages. Example data formattingtechniques including techniques involving data streaming, chunking, andthe use of other data structures in creating copies (e.g., secondarycopies) are described in U.S. Pat. Nos. 7,315,923 and 8,156,086, andU.S. Pat. Pub. No. 2010-0299490, each of which is incorporated byreference herein.

FIGS. 1F and 1G are diagrams of example data streams 170 and 171,respectively, that may be employed for performing data storageoperations. Referring to FIG. 1F, the data agent 142 forms the datastream 170 from the data associated with a client 102 (e.g., primarydata 112). The data stream 170 is composed of multiple pairs of streamheader 172 and stream payload 174. The data streams 170 and 171 shown inthe illustrated example are for a single-instanced storage operation,and a stream payload 174 therefore includes both single-instance (“SI”)data and/or non-SI data. A stream header 172 includes metadata about thestream payload 174. This metadata may include, for example, a length ofthe stream payload 174, an indication of whether the stream payload 174is encrypted, an indication of whether the stream payload 174 iscompressed, an archive file identifier (ID), an indication of whetherthe stream payload 174 is single instanceable, and an indication ofwhether the stream payload 174 is a start of a block of data.

Referring to FIG. 1G, the data stream 171 has the stream header 172 andstream payload 174 aligned into multiple data blocks. In this example,the data blocks are of size 64 Kb. The first two stream header 172 andstream payload 174 pairs comprise a first data block of size 64 Kb. Thefirst stream header 172 indicates that the length of the succeedingstream payload 174 is 63 Kb and that it is the start of a data block.The next stream header 172 indicates that the succeeding stream payload174 has a length of 1 Kb and that it is not the start of a new datablock. Immediately following stream payload 174 are an identifier header176 and identifier data 178 pair. The identifier header 176 includes anindication that the succeeding identifier data 178 includes theidentifier for the immediately previous data block. The identifier data178 includes the identifier that the data agent 142 generated for thedata block. The data stream 171 also includes other stream header 172and stream payload 174 pairs, which may be for SI data and/or for non-SIdata.

FIG. 1H is a diagram illustrating the data structures 180 that may beused to store blocks of SI data and non-SI data on the storage device(e.g., secondary storage device 108). According to certain embodiments,the data structures 180 do not form part of a native file system of thestorage device. The data structures 180 include one or more volumefolders 182, one or more chunk folders 184/185 within a volume folder182, and multiple files within a chunk folder 184. Each chunk folder184/185 includes a metadata file 186/187, a metadata index file 188/189,one or more container files 190/191/193, and a container index file192/194. The metadata file 186/187 stores non-SI data blocks as well aslinks to SI data blocks stored in container files. The metadata indexfile 188/189 stores an index to the data in the metadata file 186/187.The container files 190/191/193 store SI data blocks. The containerindex file 192/194 stores an index to the container files 190/191/193.Among other things, the container index file 192/194 stores anindication of whether a corresponding block in a container file190/191/193 is referred to by a link in a metadata file 186/187. Forexample, data block B2 in the container file 190 is referred to by alink in the metadata file 187 in the chunk folder 185. Accordingly, thecorresponding index entry in the container index file 192 indicates thatthe data block B2 in the container file 190 is referred to. As anotherexample, data block B1 in the container file 191 is referred to by alink in the metadata file 187, and so the corresponding index entry inthe container index file 192 indicates that this data block is referredto.

As an example, the data structures 180 illustrated in FIG. 7 may havebeen created as a result of two storage operations involving two clients102. For example, a first storage operation on a first client 102 couldresult in the creation of the first chunk folder 184, and a secondstorage operation on a second client 102 could result in the creation ofthe second chunk folder 185. The container files 190/191 in the firstchunk folder 184 would contain the blocks of SI data of the first client102. If the two clients 102 have substantially similar data, the secondstorage operation on the data of the second client 102 would result inthe media agent 144 storing primarily links to the data blocks of thefirst client 102 that are already stored in the container files 190/191.Accordingly, while a first storage operation may result in storingnearly all of the data subject to the storage operation, subsequentstorage operations involving similar data may result in substantial datastorage space savings, because links to already stored data blocks canbe stored instead of additional instances of data blocks.

If the operating system of the secondary storage computing device 106 onwhich the media agent 144 resides supports sparse files, then when themedia agent 144 creates container files 190/191/193, it can create themas sparse files. As previously described, a sparse file is type of filethat may include empty space (e.g., a sparse file may have real datawithin it, such as at the beginning of the file and/or at the end of thefile, but may also have empty space in it that is not storing actualdata, such as a contiguous range of bytes all having a value of zero).Having the container files 190/191/193 be sparse files allows the mediaagent 144 to free up space in the container files 190/191/193 whenblocks of data in the container files 190/191/193 no longer need to bestored on the storage devices. In some examples, the media agent 144creates a new container file 190/191/193 when a container file190/191/193 either includes 100 blocks of data or when the size of thecontainer file 190 exceeds 50 Mb. In other examples, the media agent 144creates a new container file 190/191/193 when a container file190/191/193 satisfies other criteria (e.g., it contains fromapproximately 100 to approximately 1000 blocks or when its size exceedsapproximately 50 Mb to 1 Gb).

In some cases, a file on which a storage operation is performed maycomprise a large number of data blocks. For example, a 100 Mb file maybe comprised in 400 data blocks of size 256 Kb. If such a file is to bestored, its data blocks may span more than one container file, or evenmore than one chunk folder. As another example, a database file of 20 Gbmay comprise over 40,000 data blocks of size 512 Kb. If such a databasefile is to be stored, its data blocks will likely span multiplecontainer files, multiple chunk folders, and potentially multiple volumefolders. As described in detail herein, restoring such files may thusrequiring accessing multiple container files, chunk folders, and/orvolume folders to obtain the requisite data blocks.

Example Storage Systems Including Client-Side Repositories

Examples of systems and methods will now be described for usingclient-side signature to improve data storage operations. Whiledescribed in some cases with respect to certain types of operations(e.g., backup and restore operations) for the purposes of illustration,the deduplication and collaborative data movement techniques describedherein may be equally compatible with other types of storage operationsincluding archive, snapshot, and replication operations, to name a few.Descriptions of embodiments of these and other types storage operationscompatible with embodiments described are provided above.

FIG. 1I shows a block diagram illustrative of an embodiment of anetworked storage system 100. In the illustrated embodiment of FIG. 1I,the storage system 100 can further include one or more client-sidesignature repositories 121 and one or more signature generators 123.

The client-side signature repository 121 can include a data storecontaining data block signatures corresponding to data blocks that formthe primary data residing in the primary storage subsystem 117, as wellas a processing module or agent, which generally maintains the datastore, and can perform functions associated therewith (e.g., signaturecomparison). As shown in the illustrated embodiment of FIG. 1I, theclient-side signature repository 121 can form part of or reside on theclient 102. For instance, the data store of the client-side signaturerepository 121 forms part of the primary storage device 104 of theclient 102, and the agent of the client-side signature repository 121executes on one or more processors of the client 102.

As will be described further with respect to FIG. 1J, in certain otherembodiments, the client-side signature repository 121 can be separatefrom the client(s) 102. For instance, data store of the client-sidesignature repository 121 is implemented using one or more data storesthat are separate from the primary storage devices 104 of the clients102. Similarly, in other embodiments, the agent of the client-sidesignature repository 121 can be implemented on a computing device thatis separate from the client 102. In such cases, the computing device onwhich the processing module of the client-side repository 121 and/or thestorage device on which the data store of the client-side repository 121are implemented on can communicate with the client(s) 102 via a network(e.g., a LAN). In some embodiments, each client 102 communicates with aclient-side signature repository 121 that is dedicated to thatparticular client 102. In certain other embodiments, multiple clients102 (e.g., some or all of the clients) communicate with a common, sharedclient-side signature repository 121. In yet further embodiments, eachclient includes a client-side signature repository 121 to track thesignatures stored thereon, and the system 100 also includes aclient-side signature repository 121 that is common to multiple clients102 (e.g., some or all of the clients).

The signature generator 123 may be a software module that is generallyresponsible for generating signatures of the data blocks residing in theprimary storage subsystem 117, e.g., primary storage devices 104associated with the clients 102. The signatures generated by thesignature generator 123 can be used to uniquely identify the data blockswithin the client 102 or determine when two or more data blocks areidentical. The signatures can be generated using a variety oftechniques, such as a hash function, as will be described in greaterdetail below with reference to FIG. 2A.

FIG. 1J illustrates a block diagram of another embodiment of a storagesystem 100. Unlike the embodiment depicted in FIG. 1I, the embodimentshown in FIG. 1J includes a client-side signature repository 121 that iscommon to multiple clients 102A-102C. For instance, the client-sidesignature repository 121 may be implemented on a computing device and/orstorage device distinct from the one or more clients 102A-102C. For thesake of simplicity, not all of the components and subcomponents of thesystem 100 are illustrated in FIG. 1J. For example, while not shown, thesystem 100 of FIG. 1J may include a storage manager 140, data agent(s)142, secondary storage computing device(s) 106, or other componentsshown in FIGS. 1A-1I.

In some embodiments, the client-side signature repository 121 is inrelatively close physical proximity to the clients 102 as compared tothe secondary storage subsystem 118, and communicates with the clients102 using a different network topology than the topology used forcommunication between the components in the primary storage subsystem117 and the components in the secondary storage subsystem 118. Forexample, in an embodiment, the clients 102 communicate with theclient-side signature repository 121 over a LAN and communicate withcomponents in the secondary storage subsystem 118 (e.g., the mediaagents 144 and/or the secondary storage devices 108) over a WAN. Incertain embodiments, communication between the clients 102 and theclient-side signature repository 121 takes place at a higher data rateand/or with lower latency than communication between the clients 102 andthe components in the secondary storage subsystem.

Referring again to FIG. 1I, the client-side signature repository 121 canbe used by the system to store signature information relating to datablocks or primary data units of other granularity stored in the primarystorage subsystem 117. Furthermore, depending on the embodiment, theclient-side signature repository 121 can store the correspondingsignatures of all, or substantially all of the data blocks found in theprimary storage subsystem 117. For instance, where a client-sidesignature repository 121 is dedicated to a particular client 102, theclient-side signature repository 121 retains signatures corresponding toall or substantially all (e.g., at least 90 percent, at least 95percent, or at least 99 percent) of the data blocks in the primarystorage device 104 associated with that client 102. Where theclient-side signature repository 121 is shared, the client-sidesignature repository 121 retains signatures corresponding to all orsubstantially all of the data blocks in the data stores of all theclients 102 that share the client-side signature repository 121.Accordingly, the client-side signature repository 121 can function as anindex or global map of the data blocks that form the primary data. Inother cases, the client-side signature repository 121 operates as acache, and signatures are deleted from the client-side signaturerepository 121 on a first-in first-out or other some other basis.

The system 100 can generate or update the signature information in theclient-side signature repository 121 according to any appropriateschedule. As one example, the system 100 can generate or update theclient-side signature repository 121 each time primary data is writtenor modified in a primary storage device 104 associated with a client102. For example, when data is written to or modified in a primarystorage device 104, the system 100 can generate a signature for theconstituent data blocks.

In some embodiments, the client-side signature repository 121 stores asingle record for each unique signature. Incoming generated signaturesare compared with signatures already stored in the client-side signaturerepository 121. If a signature is already located in the client-sidesignature repository 121, the record for that signature is updated withthe information corresponding to the newly written or modified datablock. If the signature is not already located in the client-sidesignature repository 121, a new record is generated for that data block.Techniques for organizing the client-side signature repository 121 aredescribed in further detail with respect to FIGS. 2A-2B.

In some embodiments, the storage system 100 uses the client-sidesignature repository 121 to minimize or otherwise reduce the amount ofdata that is transmitted to secondary storage during backup or othersecondary copy operations. Some examples of secondary copy operationsthat utilize client-side signature information are described herein,e.g., with respect to FIGS. 3-7.

Additionally, in some embodiments, the system 100 improves theefficiency of restore operations to a target client 102 by using theclient-side signature repository to determine which data blocks in arestore data set are already located in primary storage. Furtherexamples of restore operations that utilize client-side signatureinformation are described herein, e.g., with respect to FIGS. 8-11.

Example Signature Repository

FIG. 2A is a block diagram illustrative of an expanded view of aclient-side signature repository 121 including an agent 202 and a datastore 204. Generally speaking, the agent 202 may be implemented as asoftware module that communicates with the other components of thestorage system 100 (e.g., the primary storage devices 104, the storagemanager 140, the clients 102, the media agents 144, and/or secondarystorage devices 108, and conveys data to and from the signaturerepository 204. Furthermore, the client-side signature repository agent202 can perform the various processing steps described herein that areattributed to the client-side signature repository 121. For example, theclient-side signature repository agent 202 generally maintains thesignatures and corresponding information in the data store 204, and canalso access and process the signature information in the data store 204to determine data blocks do and do not reside in the primary storagedevices 104.

The data store 204 can be stored on one or more storage devices of anyof the types described herein (e.g., solid state memory, disk drives orother magnetic media, or the like).

While the signature information in the data store 204 can be organizedin a variety of ways, in certain embodiments, the signature informationis arranged as a plurality of signature blocks 206 as shown in FIG. 2A.Each signature block 206 corresponds to a unique or substantially uniquedata block signature 208 and corresponding data block.

Each signature block 206 in some embodiments includes informationrelating to copies of the corresponding data blocks stored in a subsetof one or more of the clients 102. In other embodiments, each signatureblocks 206 includes information relating to all of the copies of thecorresponding data block that are stored in the primary storagesubsystem 117, e.g., across all of the primary storage devices 104.

Signature blocks 206 stored in the signature repository 204 can includevarious pieces of information, or metadata, corresponding to the copiesof the corresponding data block that reside in the primary storagesubsystem 117. For example, each signature block 206 can include asignature field 208 including the data block signature, a number ofinstances field 210 that identifies the number of instances or copies ofthe data block that exist on a particular client (group of multipleclients, or within the entire primary storage subsystem 117, dependingon the embodiment), a copy operation flag 212, and entries 214 eachcorresponding to a different instance or copy of the data block. Theentries 214 can further include a location information field 218, anaccess/priority information field 220, and an age information field 222.These various types of information and fields will be described below ingreater detail.

Each signature block 206 can include additional or less information asdesired. Moreover, in some other embodiments the client-side signaturerepository 121 can be organized differently. For instance, while theillustrated embodiment generally groups entries for the data blockinstances into a separate signature block 206 for each unique signature,other embodiments may instead organize the entries according to someother scheme. For instance, entries may be grouped based on the client102 that stores the corresponding data block entries, based on the timethe data block instance was added to the primary storage subsystem 117,or any other appropriate scheme. In some such cases, where there aremultiple copies of a particular data block stored within the primarystorage subsystem 117, the client-side signature repository 121 maymaintain multiple copies of the corresponding unique signature—one foreach copy of the corresponding data block.

Generally speaking, the data block signatures 208 are used as areference to identify corresponding data blocks and/or determine whetherthe corresponding data blocks are already stored in the primary storagesubsystem 117. The signature in the signature field 208 can be derivedby performing a hash or other function on the corresponding data block.In some embodiments, the signature 208 is generated by the signaturegenerator 123 of the client 102 (FIG. 1I). However, the signature can begenerated by a variety of different components, depending on theimplementation, such as the agent 202 of the client-side signaturerepository 121, the storage manager 140, the media agent 144, and/or amodule executing on a primary storage device 104. In some embodiments,signatures 208 are derived each time data is written to or modified on aprimary storage device 104. In other cases, signatures 208, aregenerated in association with a backup, restore, or other storageoperation, or based on some other appropriate schedule. In anembodiment, the SHA-512 algorithm is used (e.g., on a 64 kB or 128 kBdata block) to derive the signature 208. The resulting signature is 256bytes, and can be used for deduplication purposes. Hash functions otherthan SHA-512 can be used on the data blocks to derive the signature, aswell as other non-hash functions. In addition, different sizedsignatures may be used. Additionally, the secondary storage subsystem118 can also include signature information in some embodiments. Forinstance, signatures for backed up, archived, or otherwise copied datablocks residing in the secondary storage devices 108 are maintained inthe secondary storage subsystem 118 in certain embodiments.

FIG. 2B is a block diagram illustrative of an expanded view of anexample of an entry 216 of a signature block 206 from FIG. 2A. In theillustrated example, each entry includes an instance ID field 216, alocation information field 218, an access/priority information field220, and an age information field 222.

The instance ID field 216 can include an identifier for a particularinstance (i.e., copy) of the data block stored in the primary storagesubsystem 117, e.g., in a primary storage device 104 associated with aparticular client or subset of clients. In some embodiments, theinstance ID field 216 includes sourcing order information.

The location information field 218 can include information specifyingthe location of the data block instance in the primary storage subsystem117. For instance, where the signature block 206 includes informationrelating to a data block for which multiple separate instances arestored in the primary storage subsystem 117 in association with multipleclients 102, the location information can include a client ID indicatingthe client 102 where the instance of the data block is located. Thus,the client ID field can be useful where the system includes a sharedclient-side signature repository 121 that maintains signatureinformation for multiple clients 102. In some cases, such as where eachclient 102 maintains its own client-side signature repository 121 andthere is not a shared client-side signature repository 121, the clientID field may not be included. The location information can additionallyinclude physical and/or logical memory address information usable toaccess the instance of the data block within the primary storage device104 or other data store where the instance of the data block is stored.

In addition to providing location information, each entry can provideaccess and priority information in an access/priority field 220. Theaccess/priority information can be used to rank or prioritize thedifferent instances of the data block for sourcing purposes. Forinstance, where multiple copies of a particular data block are stored inthe primary storage subsystem 117 (e.g., in data stores for multipleclients 102), the access/priority information can be used by the system100 to determine which copy of the data block to access for a storageoperation (e.g., a backup or restore operation) or other purpose. Suchtechniques are described in greater detail below with reference to FIG.12. The access/priority field 220 can include information regardingcharacteristics of the data store and/or client where the copy of thedata block is located. For example, the access/priority field 220 caninclude information regarding the following for the data store thatstores the copy of the data block and/or the associated client 102,without limitation: type and age information, speed or performanceinformation (e.g., hardware capability information), response time, typeor version information for installed software or firmware, storagecapacity, client operating system information, processing load (e.g.,current or average processing load), etc. Some of these types ofinformation can be used to determine a relative access speed forretrieving a copy of a particular instance of a data block.

The access/priority field 220 can also include information regarding thenetwork associated with the data store. For example, the access/priorityfield 220 can include information regarding the network bandwidth andspeed between the data store and various target clients within thestorage network. The access/priority field 220 can also provideinformation regarding downtime or scheduled maintenance of the datastore, etc. The data store information and network information can beused to determine an expected overall response time of a particularclient.

The access/priority field 220 can also include a priority level rankingof the client 102 identified by the client ID. A higher priority levelranking can indicate that it is less desirable to source data from aparticular client because of the relative importance of applicationsexecuting thereon, the user of the client, or other reasons. Theinformation can also be used to generate the sourcing rank for eachentry 214, as described in greater detail below with reference to FIG.12. In some cases, information other than the information in theaccess/priority field 220 can be used in determining which instance ofthe data block to source, such as the information in the instance IDfield 216.

Each entry 214 can also include age information in an age field 222. Theage field 222 can be used to determine how long a particular instance ofa data block has existed in the primary storage subsystem 117. Forexample, it may be generally preferable to use newer instances insteadof older entries, or vice versa. The age field 222 in one embodimentincludes an age ID which is an alphanumeric indication of when the entry214 was added or revised relative to other data blocks. For instance,the age ID may be a unique identifier for the particular data block orinstance of the data block, or may be a unique identifier associatedwith a particular storage operation, such as a backup, backup catalog,or other storage operation associated with the entry.

In some instances, the client-side signature repository 121 candetermine that a particular entry 214 is a new entry if the age field222 indicates that it was added to the client-side signature repository121 after a previous backup operation. Further, if the particular entry214 is the first entry for a signature block 206, the system 100, incertain embodiments, can determine that the data block and correspondingsignature are new to the primary storage subsystem 117 and therefore donot yet reside in the secondary storage subsystem 118. If the systemdetermines that the entry 214 resided in the client-side signaturerepository 121 prior to a previous secondary copy operation thatinvolved the data block corresponding to the entry 214, the system, insome embodiments, can determine that the instance of the data blockcorresponding to the entry 214 has already been copied to the secondarystorage subsystem 118 (e.g., has already been involved in a back up).

Because the clients 102 are frequently generating and modifying primarydata stored in the primary storage devices 104, it can in some cases bebeneficial to track whether a signature block 206 has been modifiedsince a previous backup. This can be done using a copy operation flag212. The copy operation flag 212 can indicate the time and/or date of aprevious copy operation, whether the signature block 206 has beenmodified since a previous copy operation, whether the data blockcorresponding to the signature block has been part of a previous copydata set and stored in the secondary storage subsystem 118 (e.g., thesignature block is not a new signature block), or any combinationthereof. For example, during a copy operation, the system 100 canidentify signature blocks that have been modified since a previousbackup by referring to the copy operation flag 212. By identifyingsignature blocks that have been modified, the system 100 can identifydata corresponding to the modified signature blocks that has changedand/or data that may be unique to the primary storage subsystem 117(e.g., does not reside or is unlikely to reside in the secondary storagesubsystem 118). Thus, in some embodiments, rather than reading the datain a copy data set to identify data that may be unique to the primarystorage subsystem 117 and/or has changed, the system 100 can refer tothe signature information in the client-side signature repository 121corresponding to the data in the copy data set. In this manner, thesystem 100 can reduce the amount of data being read and time spent toidentify modified data, and can more quickly identify which data mightbe unique to primary storage, e.g., for performing a deduplicatedsecondary copy.

Further, the copy operation flag 212 can indicate that the signatureblock 206 has been modified since a previous copy operation if thesignature block 206 is either new or has been revised since the previouscopy operation. For example after a copy operation is completed, thecopy operation flag 212 can be reset. Thereafter, if the signature block206 is edited, the copy operation flag 212 can be set, indicating thatthe signature block 206 may contain information that has not yet beeninvolved in a copy operation. Furthermore, each time a new signatureblock is generated, the copy operation flag can 212 can be setindicating that the signature block and corresponding data block havenot been involved in a copy operation.

The signature block 206 and/or corresponding entries 214 can containfewer or more pieces of information than what is illustrated in theexamples shown in FIGS. 2A and 2B. For example, the signature block 206can include date data, such as the date when the signature block 206 wascreated or modified, etc. In some embodiments, the entries 214 includefile identifiers that indicate to which file an entry 214 belongs. Thefile identifiers can be located in the location field 218, in anotherfield, or in a separate field. Furthermore, the entries 214 can includeorganizational data that indicates where the data block corresponding tothe entry 214 is located with respect to other data blocks in aparticular file, etc.

FIG. 3 is a flow diagram illustrative of one embodiment of a routineimplemented by a storage system 100 for performing a secondary copyoperation (e.g., a backup, archive, or snapshot operation) using aclient-side signature repository 121.

At block 302, a request is received to perform a secondary copyoperation for a data set associated with a first client computing device102 of plurality of client computing devices 102. For instance, astorage policy implemented on a storage manager 140 may trigger asecondary copy operation on a scheduled basis, or a user can trigger asecondary copy operation via interaction with a user interface. In oneembodiment, the storage manager 140 forwards an instruction to performthe secondary copy to a data agent 142 executing on the first clientcomputing device 102. The copy data set can generally be any grouping ofdata associated with the first client 102, and can include one or morefiles, directories, or the like. In one embodiment, the client data setincludes one or more sub-clients, as described herein.

At block 304, the storage system 100 generates signatures for theindividual data blocks in the copy data set. Depending on theembodiment, the signatures can be generated by different entities in thestorage system 100. For example, in one embodiment, a signaturegenerator 123 on the first client 102 generates the signatures locally.As another example, signatures can be generated by the client-sidesignature repository 121, which can be separate from and/or remote fromthe client(s) 102.

At block 306, the agent 102 of the client-side signature repository 121(or other appropriate component) consults the signature repository 204to locate data blocks in the copy data set within the primary storagesubsystem 117. For instance, while the first client 102 may store actualcopies of all data blocks in the copy data set, it may be useful tosource the data blocks from data stores associated with other ones ofthe clients 102 for the purposes of creating and transmitting thesecondary copy, as described previously.

At block 308, the storage system 100 determines which client(s) tosource the individual data blocks from to compile the copy data set. Forexample, the agent 102 may access information in the client-sidesignature repository 204 associated with copies of the individual datablocks that reside in the primary storage subsystem 117. Suchinformation can include any type of information sufficient to selectparticular copies of the data block to source, and in some embodimentsincludes information organized along the lines of the signature blocks206 of FIGS. 2A and 2B, such as the access/priority information 220and/or age 222 information. Where there are multiple copies of a datablock within the primary storage subsystem 117, the agent 202 maycompare the accessed information to a sourcing policy or other criteriato determine which copy to source for inclusion in the copy data set.Additional techniques for determining which copy of the data block tosource for the purposes of compiling a copy (or restore) data set aredescribed herein, e.g., with respect to FIG. 12.

At block 310, the data blocks in the copy set are sourced from theclients 102 as determined at block 308. Depending on the sourcingdeterminations, a first subset of one or more data blocks may be sourcedfrom the first client 102 and the remainder of the data blocks may besourced from one or more second clients 102. Depending on the sourcingdetermination for any particular copy operation, a variety of scenariosare possible. For instance, in some cases, all data blocks may besourced from the first client 102. Conversely, all of the data blocksmay in other scenarios be sourced from one or more clients 102 otherthan the first client 102. In order to access the data blocks within theprimary storage subsystem 117, the agent of 202 of the client-sidesignature repository 121 may refer to other information in the signaturerepository 121 in addition to the signature 208, such as the locationinformation 218 of the signature block 206 described with respect toFIGS. 2A and 2B.

At block 312, the accessed data blocks are forwarded from the primarystorage subsystem 117 to the secondary storage subsystem 118. Forexample, all of the sourced data blocks in the data set may be forwardedto the agent 102 of the client-side signature repository 121 or to someother central or shared location within the primary storage subsystem117 for forwarding to a media agent 144. In some cases, a data agent orother entity receives the data blocks and compiles the data blocks intoa packaged (e.g., formatted) copy data set before sending to the mediaagent 144. In other embodiments, each source client 102 forwards thedatablocks it is responsible for directly to the secondary storagesubsystem 118.

At block 314, the media agent 144 or other appropriate component withinthe secondary storage subsystem 118 creates the secondary copy byconveying the data to one or more secondary storage devices 108 forstorage.

FIG. 4 is a state diagram illustrative of the interaction between thevarious components of the storage system 100 with respect to anexemplary collaborative copy operation where a copy data set associatedwith a target client 102B is sourced from multiple clients 102,including one or more clients 102A, 102C other than the target client102B. For purposes of the example, the illustrated embodiment has beensimplified to include interaction between the clients 102, one mediaagent 144, and one storage device 108. In other embodiments, any of themedia agents 144 and any of the storage devices 108, alone or incombination, can be used for performing a collaborative copy operationfrom any combination of the clients 102.

A collaborative copy operation (or other storage operation) can beinitiated in many different ways, such as at predetermined timeintervals, upon client request, upon storage manager 140 request, etc.For example, a storage policy associated with the client 102B maydictate that a copy operation occur daily, weekly, monthly or at someother predetermined time interval. Alternatively, the copy operation canoccur based on manual selection by a system administrator via userinterface.

In the illustrated example, signatures are generally generated locallyby the individual clients 102. Thus, as part of the current copyoperation, the signature generator 123 of the subject client 102Bgenerates signatures for data blocks in the copy data set (1A). Theclient forwards (1B) the generated signatures to the client-sidesignature repository 121. The agent (not shown) of the client-sidesignature repository 121 in some cases may update the information in thesignature repository 204 as appropriate, e.g., to add entries 214corresponding to the data blocks in the copy data set. In other cases,the entries 214 were added previously, such as at the time the data wasoriginally written to the primary storage device 104 of the targetclient 102B.

Before the current copy operation, the client-side signature repository121 already included entries corresponding to some or all of the datablocks previously stored in the primary storage devices 104 associatedwith the set of clients 102. Although in the illustrated embodiment theclient-side signature repository 121 is shared by multiple clients, insome embodiments, each of the clients 102 is associated with its ownclient-side signature repository 121. Furthermore, in certain otherembodiments, the client-side signature repository 121 generates the datablock signatures instead of the client signature generators 123.

The client-side repository 121 processes (2) the received signatures inthe copy data set to determine where to source the data blocks from inthe primary storage subsystem 117 for the purposes of sending to thesecondary storage subsystem 118, i.e., to carry out the copy operation.In some cases, such as where the copy operation is a deduplicated copyoperation, the client-side signature repository 121 (2) processes thesignatures information related to the data blocks in the copy data setto identify for transmission to the secondary storage subsystem 118 onlythose the data blocks that are unique to the primary storage (that don'texist in the secondary subsystem).

The client-side repository 121 (or other appropriate entity such as adata agent 142 of the client 102B) in some embodiments transmits (3) acopy data set index (FIGS. 13-14) to the media agent 144. As will bedescribed in greater detail herein, the copy data set index may be adata structure including metadata forming a map of the secondary copy,specifying the data blocks in the copy as well as their relativeorganization. In the illustrated example, one or more of the clients 102forward copies of the data blocks that form the copy data set to thesecondary storage subsystem 118. For instance, once the client-siderepository 121 determines which clients 102 the individual copies of thedata blocks in the copy data set are going to be sourced from, theclient-side repository 121 (or other appropriate component such as thestorage manager 140) instructs those source clients 102 to forwardcopies of those data blocks to the media agent 144. In otherembodiments, the data blocks that form the copy data set are accumulatedat a central location (e.g., at the client-side repository 121), and theentire copy data set is sent as a group to the media agent 144.

As shown, the target client 102B as well as one or more non-targetclients 102A, 102C may be selected as sources for at least some of thedata blocks. The client-side signature repository 121 may instruct therespective clients (4A, 4B, 4C) to forward copies of the data blocksthat are going to be sourced from each respective client 102 to thesecondary storage subsystem 118. In turn, the target client 102Bforwards (5A) the requested data blocks to the media agent 144 or otherappropriate component in the secondary storage subsystem 118. Where atleast some of the data blocks are to be sourced from clients 102A, 102Cother than the target client 102B, e.g., based on a data sourcingpolicy, those data blocks are forwarded (5B), (5C) by the non-targetclients 102A, 102C to the media agent 144. Example data sourcingpolicies will be described in greater detail below with reference toFIG. 12. In this manner, resource utilization in the primary storagesubsystem 117 can be allocated as desired. For instance, the amount ofprocessing performed by the target client 102B and/or the amount ofdowntime of the target client 102B to perform the copy operation can bereduced.

The media agent 144 (6) processes the data received from the primarystorage subsystem 117. To process the data, the media agent 144 canstore the copy data set index or other map of the files and data withinthe secondary copy. Once the media agent 144 has processed the receiveddata, the media agent creates (7) the secondary copy by writing the copydata set to the storage device(s) 108.

One skilled in the art will appreciate that all of the components ofstorage system 100 are not necessary to perform the copy operation, andthat the processes described herein can be implemented in any number ofways without departing from the spirit and scope of the description. Forexample, one or more of the clients 102, the storage manager 140, oranother appropriate component may perform the functions described inassociation with the client-side signature repository.

FIG. 5 is a flow diagram illustrative of an embodiment of a routine 500implemented by a storage system 100 for updating a client-side signaturerepository 121. For example, routine 500 can apply to embodimentsdescribed with reference to FIGS. 1A-1J, 2A, and 2B. While specificsteps of the example routine 500 provided below are described as beingperformed by a particular component of the storage system 100, the stepsof the routine 500 can generally be implemented by other components inother embodiments, such as any one, or a combination, of the storagemanager 140, one or more of clients 102, the agent 202 of theclient-side signature repository 121, one or more media agents 144,and/or one or more of the secondary storage devices 108.5

At block 502, the storage system 100 tracks storage operationsassociated with one or more of the clients 102. The storage operationsmay include, but are not limited to the generation of a new file, themodification of an existing file, the deletion of an existing file, thesaving of a file, etc. For instance, the clients 102 may track their ownstorage operations, or central, shared component, such as the agent 202of the client-side signature repository 121 may track the storageoperations for multiple ones of the clients 102.

At block 504 the storage system 100 identifies data that has beenmodified within a primary storage device 104 as a result of trackedprimary storage operation (e.g., a newly written or modified file). Forinstance, to identify the data that has been modified, the storagesystem 100 can detect or otherwise track or identify each write to thedata store. In some instances, each time data is written to or deletedfrom the primary storage device 104, the storage system 100 records thelocation of the data that has been modified within the primary storagedevice 104, as well as additional information. Furthermore, the system100 can identify the data blocks corresponding to modified data. Forexample, a file may be formed from six data blocks. A user may edit andsave the file. Upon saving the file, the first five data blocks remainthe same, but the sixth data block changes and an additional four datablocks can be added (for a total of ten data blocks). The storage system100 can identify the file and/or the data blocks that have changedtogether as a group, or can identify the data blocks separately on anindividual basis. Furthermore, the system 100 can track the storagelocation of the data blocks that make up the file.

At block 506, the storage system 100 generates signatures for the datablocks that make up the identified data. As discussed in greater detailabove with reference to FIG. 2A, the signature can be generated using ahash function, or some other function capable of uniquely identifyingthe data blocks or substantially uniquely identifying the data blocks.In some embodiments the storage system 100 can generate the signaturefor the data blocks during or otherwise in association with the storageoperation. In certain embodiments the storage system 100 generates thesignature for the data blocks after the storage operation has beencompleted. In other embodiments, signatures for newly added or modifieddata can be generated at some other time, e.g., based on a preferenceincluded in a storage policy. For example, a storage policy can specifya frequency with which signatures should be generated for data blockscorresponding to modified data. Or a storage policy can specify thatsignatures are generated once a particular application has been closed,once a client computer is to be shut down, once a day, or some otherinterval, as desired. In one embodiment, signatures are generated localto each client 102 by the signature generator 123 residing on the client102. In other cases, signatures 123 are generated by a shared component,such as the agent of the client-side signature repository 121.

At block 508 the storage system 100 updates the client-side signaturerepository 121. For instance, the agent 202 of the client-side signaturerepository 121 (or other appropriate component) can determine if (1) agenerated signature is new to the client-side signature repository 121,or if instead (2) the client-side signature repository 121 alreadyincludes the signature. For instance, where the client-side signaturerepository 121 is organized using signature blocks 206, if theclient-side signature repository 121 includes the generated signature,it will already include a signature block 206 for that signature, andthe agent 202 can revise the existing signature block 206 to add anentry 214 corresponding to the newly added data block instance.

In some instances, such as when a data block has been overwritten ordeleted, the agent 202 can remove an entry from a signature block 206.Also, if a generated signature is not already included in theclient-side signature repository 121, the client-side signaturerepository 121 can generate a new signature block 206 containing the newsignature as well as an entry with additional information regarding thedata block used to generate the signature as discussed in greater detailabove with reference to FIGS. 2A and 2B. As mentioned previously, theclient-side signature repository 121 can include signaturescorresponding to data blocks found in one client or multiple clients.

Furthermore, if the storage system 100 determines that a data block hasbeen removed and the entry being deleted is the last entry of asignature block 206, in certain embodiments, the storage system 100 canremove the signature block from the client-side signature repository121. In this way, the client-side signature repository 121 accuratelyrepresents the data currently residing in the primary storage subsystem117.

One skilled in the art will appreciate that routine 500 can includefewer, more, or different blocks than those illustrated in FIG. 5. Forexample, the storage system 100 can update the client-side signaturerepository 121 based on a storage policy, a user request, identifiedstorage operations, etc. The storage policy can indicate a predefinedschedule when the client-side signature repository 121 should beupdated. For example, the client-side signature repository 121 can beupdated every five minutes, every hour, at the end of each day orbusiness day, at the end of each week, etc. In some embodiments theclient-side signature repository 121 is updated each time the clientcomputer is to be shut down. Moreover, the described steps may beperformed differently in some embodiments. For instance, the agent 202of the client-side signature repository 121 may decide to retain asignature block 206 in some cases even where the only copy of thecorresponding data block in the primary storage subsystem 117 isdeleted. In this way, the client-side signature repository 121 canadditionally track data blocks that have previously resided in primarystorage. In such embodiments, the signature block 206 can include a flagindicating that no copies of the corresponding data block currentlyreside in the primary storage subsystem 117. For example, the indicatorcan simply be that the instances field 210 indicates zero entries. Incertain embodiments, the agent 202 of the client-side signaturerepository 121 determines whether or not a signature block with zeroentries should be deleted based on whether or not an instance of thecorresponding data block was previously copied to the secondary storagesubsystem 118 (e.g., as part of a backup operation). If the data blockhas been previously copied to the secondary storage subsystem 118, theclient-side signature repository 121 may decide not to delete thesignature block 206, whereas, if the client-side signature repository121 determines that the data block was not previously copied to thesecondary storage subsystem 118, the client-side signature repository121 may decide to delete the signature block 206, or vice versa, asdesired.

FIG. 6 is a state diagram illustrative of the interaction between thevarious components of an example of the storage system 100 with respectto a secondary copy operation (e.g. a backup operation, snapshotoperation, auxiliary copy operation, archive operation, etc.) where datablocks are sourced only from the target client 102B. The copy operationmay be a deduplicated operation, as will be described. For purposes ofthe example, the illustrated embodiment has been simplified to includeinteraction between one client 102B, 102A, one media agent 144, and onestorage device 108. In other embodiments, any of the media agents 144and storage devices 108, alone or in combination, can be used forperforming a copy operation from any combination of the clients 102.

The client 102B (1A) generates signatures of data blocks correspondingto data that has been modified within the primary storage device 104,and (1B) updates the client side repository 121 with the generatedsignatures. Although in the illustrated embodiment there is oneclient-side signature repository 121 for three clients 102, in someembodiments, each of the clients 102 is associated with its ownclient-side signature repository 121. Furthermore, in certainembodiments, the client-side signature repository 121 generates thesignatures for the one or more clients with which it is associated, andthose clients 102 do not generate the signatures locally.

In an embodiment, the system 100 initiates a copy operation for a copydata set (e.g., of one or more files, file system volumes, etc.) storedwithin a primary storage device 104 of a target client 102B. Uponinitiating the copy operation, the client-side signature repository 121(2) processes the copy operation request and identifies data blocks tosend to the secondary storage subsystem 118 as part of the copyoperation.

For instance, the client-side signature repository 121 can be used tocarry out a deduplicated copy operation, where only those data blocksunique to the primary storage subsystem 117 (i.e., do not already residein the secondary storage subsystem 118) that are part of the copy dataset are sent to the secondary storage subsystem 118.

The copy data set for any of the embodiments described herein can varydepending on the type and scope of the copy operation being performed.For example, the copy operation can be a full backup or incrementalbackup of either the entire data store or only portions thereof (e.g.,one or more files, folders, etc.). In a full backup of the entireprimary storage device 104, the copy data set can include the entiredata set found in the primary storage device 104 associated with theclient 102B. In an incremental backup of the primary storage device 104,the copy data set can include all of the data in the primary storagedevice 104 that has changed since a previous backup. Similarly, for afull or incremental backup of one or more files, the copy data set caninclude all the data in the one or more files or the data in the one ormore files that has changed since a previous backup, respectively.

As mentioned, the client-side signature repository 121 can identify thedata blocks unique to primary storage that correspond to the copy dataset. In this example, the data blocks unique to primary storage refer tothe data blocks stored in the storage device 104 associated with theclient 1028 but not found in the secondary storage subsystem 118.However, in some embodiments, the data blocks unique to the primarystorage refers to data blocks that are in any of the clients 102 butthat do not already reside in the secondary storage subsystem 118. Forexample, if the copy operation request is for full or incremental backupof a single file of the client 102B, the client-side signaturerepository 121 identifies the data blocks unique to primary storage thatform at least a portion of the single file.

In some embodiments, to identify the data blocks that are unique toprimary storage, the client-side signature repository 121 identifiessignature blocks that have been modified since a previous copyoperation. For example, the client-side signature repository 121identifies signature blocks with a copy operation flag 212 set toindicate that the signature block has been modified since a previouscopy operation.

In certain embodiments, the client 102B or the media agent 144 identifythe data blocks that are unique to primary storage by reviewingsignature block information. For example, in a full backup of the entiredata store associated with the client 102B, the client 102B or the mediaagent 144 can identify the data blocks that are unique to primarystorage using the copy operation flag 212, or by comparing a creationdate of a signature block with the date of the last copy operation.

Once the data blocks that are unique to primary storage have beenidentified, the client-side signature repository can 121 can in someembodiments (3) provide a copy data set index to the secondary storagesubsystem 118 (e.g., to the media agent 144). The copy data set indexcan provide information regarding the data blocks corresponding to thedata associated with the copy operation, as well as a map indicating therelationship between the different data blocks. One embodiment of a copydata set index is described in greater detail below with reference toFIG. 13. In some embodiments, the copy data set index is generated andcommunicated to the secondary storage subsystem 118 (e.g., to the mediaagent 144) by the client 102 whose data set is being copied rather thanthe client-side signature repository 121. In other embodiments, themedia agent 144 may generate the copy data set index.

The client 102B (4) provides the identified data blocks (e.g., thosethat are unique to primary storage subsystem 117) to the secondarystorage subsystem 118. In some embodiments, the client 1028 provides thedata blocks to the client-side signature repository 121, which in turnprovides the data blocks to secondary storage. In certain embodiments,the client-side signature repository 121 requests the client(s) 102 toprovide the identified data blocks to the media agent 144. In somecases, the media agent 144 requests the identified data blocks from theclient 102B.

Upon receiving the data blocks from the primary storage subsystem 117,the media agent 144 (5) processes the data blocks as part of the copyoperation. For instance, the media agent 144 may update its index inview of the copy operation as described herein. In some cases, the mediaagent 144 stores the copy data set index for future use. The media agent144 then conveys the copy data set to the storage device 108 for storagethereon.

One skilled in the art will appreciate that all of the components ofstorage system 100 are not necessary to perform the copy operation, andthat the processes described herein can be implemented in any number ofways without departing from the spirit and scope of the description. Inone embodiment, the client-side signature repository 121, client 102 b,or media agent 144 can identify some or all of the unique data blocks inthe primary storage subsystem 117 (that aren't already in the secondarystorage subsystem 118) regardless of whether the unique data blocks formpart of a copy data set. The unique data blocks can then be sent to themedia agent 144 (e.g., on a scheduled basis, or as part of a copyoperation along with data blocks that are associated with the copyoperation) for storage in the secondary storage subsystem 118. In thisway, the secondary storage subsystem 118 can accumulate copies of datablocks that exist in the primary storage subsystem 117, e.g., beforecertain data blocks form part of a copy data set. This technique cantake advantage of available bandwidth to simplify future deduplicatedcopy operations, for example.

FIG. 7 is a flow diagram illustrative of one embodiment of a routine 700implemented by a storage system 100 for executing a collaborative copyoperation of data using a client-side repository 121, where the copyoperation is a deduplicated copy operation. One skilled in the relevantart will appreciate that the elements outlined for routine 700 may beimplemented by one or many computing devices/components that areassociated with the storage system 100. For example, routine 700 can beimplemented by any one of, or a combination of, the storage manager 140,one or more clients 102, the client-side signature repository 121, oneor more media agents 144, and/or one or more of the storage devices 108.

At block 701, the storage system 100 receives a secondary copy operationrequest associated with a copy data set (e.g., a subclient) of a targetclient 102B, such as a request to perform a copy operation. Because thecopy operation is deduplicated, at block 702, the storage system 100identifies data blocks involved with the copy operation that are uniqueto primary storage subsystem 117 and don't already exist in thesecondary storage subsystem 118.

For the identified data blocks that are unique to primary storage, thestorage system 100 determines at block 706 consults the client-signaturerepository 121 to determine whether copies of the data block the datablock exist in the data stores of any non-target clients 102 and, if so,determines whether the data block will be sourced from another client102, or will instead be sourced from the target client 102B. To identifywhether the data block is located in another client 102, the storagesystem 100 can analyze the signature information (e.g., signature blocks206) corresponding to the data blocks in the copy data set. For example,if a signature block 206 indicates that there are multiple instances ofa data block corresponding to a particular signature in field 210,includes multiple entries 214, and/or includes multiple Client IDs inthe location field 218, the storage system 100 can determine thatmultiple copies of the data blocks exist in primary storage. Or, where ashared client-side signature repository 121 is not used and each client1-2 instead maintains its own separate client-side signature repository121, the storage system 100 can access the client-side signaturerepositories 121 of the individual clients 102 to identify whether anynon-target clients 102 have a copy of the data block.

Upon determining that a data block is to be sourced from a non-targetclient at block 704, the storage system 100 at block 706 identifies thelocation of the data block in the primary storage device(s) 104associated with that client 102. To identify the location of the datablock in the other, non-target client 102, the storage system 100 canreview the signature blocks 206 corresponding to the data blocks in thecopy data set. For example, the storage system 100 can review the entry214 corresponding to the data block located in the other client 102. Theentry 214 can include the location information of the data block withinthe other client 102.

On the other hand, if the storage system 100 determines that the datablock will be sourced from the target client 102 (e.g., because that isthe only copy of the data block), the storage system 100 identifies thelocation of the data block in the primary storage device 104 associatedwith the target client 102 at block 708. Sourcing policies fordetermining which clients 102 to source data blocks from are describedin greater detail herein, e.g., below with reference to FIG. 12.

Once the location of the identified data block that is unique to primarystorage has been identified, the storage system 100 performs the copyoperation at block 710. The data block is retrieved from the identifiedlocation in the primary storage device 104 associated with thedetermined source client 102. In addition, the signature information,such as the corresponding signature block 206 or portion thereof can beretrieved from the client-side signature repository 121 and sent to thesecondary storage subsystem 118.

While described with respect to a single data block for the purposes ofclarity, the retrieved data (data blocks and/or signature information)can be sent from their respective locations either individually orbundled together. Moreover, signatures corresponding to the data blocksthat are not unique to the primary storage subsystem 117 (already existin the secondary storage subsystem 118) are generally sent to thesecondary storage subsystem 118 instead of copies of the data blocksthemselves. The secondary storage subsystem 118 utilizes the signatureto identify the pre-existing copy of the data block in the secondarystorage device(s) 108 for use in creating the secondary copy.

One skilled in the art will appreciate that routine 700 can includefewer, more, or different blocks than those illustrated in FIG. 7.Moreover, a number of alternative embodiments are possible. Forinstance, in some cases the secondary copy operation is not adeduplicated copy operation, and copies of all of the data blocks in thecopy data set are forwarded to the secondary storage subsystem 118instead of just copies of those data blocks that are unique to theprimary storage subsystem 117.

FIG. 8 is a flow diagram illustrative of an embodiment of a routine 800implemented by a storage system 100 for using a client-side repository121 to perform a restore operation. One skilled in the relevant art willappreciate that the elements outlined for routine 800 may be implementedby one or many computing devices/components that are associated with thestorage system 800. For example, routine 800 can be implemented by anyone, or a combination of, the storage manager 140, one or more clients102, the client-side signature repository 121, one or more media agents144, and/or one or more storage devices 108.

At block 801, the storage system 100 receives a request to restore arestore data set to a target client 102B. At block 802, the storagesystem 100 receives signatures of data blocks in the restore data set.The storage system 100 can receive the signatures of the data blocks tobe restored from the media agent 144, for example. In other cases, thesignatures can be obtained from the target client 102B, the componentrequesting the restore, the storage manager 140, and/or the client-sidesignature repository 121.

For each data block to be restored, the storage system 100 determineswhether the data block is located in the primary storage subsystem 117at block 804. For instance, as described in greater detail above, withreference to FIG. 8, the storage system 100 can determine whether thedata block is located in the primary storage subsystem 117 by reviewingthe signature blocks 206 stored in the client-side signature repository121.

In some embodiments, if a signature corresponding to a data block to berestored is located in the client-side signature repository 121 or if anexisting signature block 206 has at least one entry 214, the storagesystem 100 determines that the data block is located in the primarystorage subsystem 117.

Upon determining that the data block is located in the primary storagesubsystem 117, the storage system 100 identifies the location of thedata block, as illustrated at block 806. For instance, copies of thedata block may reside in the target client 102B and/or any of the othernon-target clients 102. FIGS. 9 and 10, described below, illustrateexamples of restore operations where data is sourced from only thetarget client 1028 (FIG. 9) and where data is collaboratively sourcedfrom multiple ones of the clients 102 (FIG. 10).

On the other hand, if the information in the signature repository 116indicates that the data block is not located in the primary storagesubsystem 117, the storage system 100 can request and receive the datablock from the secondary storage subsystem 118 at blocks 808 and 810,respectively.

Once the data blocks located in the primary storage subsystem 117 havebeen identified and the data blocks not located in the primary storagesubsystem 117 have been received at the primary storage subsystem 117from the secondary storage subsystem 118, the storage system 100 canrestore the data, as illustrated in block 812. One skilled in the artwill appreciate that routine 800 can include fewer, more, or differentblocks than those illustrated in FIG. 8.

FIG. 9 is a state diagram illustrative of the interaction between thevarious components of the storage system 100 with respect to an exampleof an implementation of a restore operation. For purposes of theexample, the illustrated embodiment has been simplified to includeinteraction between one client 1028, one media agent 144, and onestorage device 108. In other embodiments, any of the media agents 144and any of the storage devices 108, alone or in combination, can be usedfor performing a restore operation of any combination of the clients102. For instance, an example of a collaborative restore operation isdescribed with respect to FIG. 10, where data is sourced from other onesof the clients 102 in performing the restore operation. Although in theillustrated embodiment the client-side signature repository 121 isgenerally central to and associated with multiple clients 102, in someembodiments, each of the clients 102 is associated with a dedicatedclient-side signature repository 121.

In an embodiment, the storage manager 140 or other appropriate componentinitiates a restore by instructing the media agent 144 a restore dataset be restored to a target client 102B. The restore request can beinitiated by one or more of the components of the storage system 100.Such a restore may initiate upon the occurrence of some predeterminedcriteria, such as a re-boot after a power outage, information storeerror, or some other condition that causes a client system to gooff-line, addition of a new client, or the like. In one embodiment, thedata from one client system 1028 can be restored to another client 102A,102C.

In response to the restore request, the client-side signature repository121 (1) receives the signatures of the data blocks in the restore dataset. The data blocks involved in the restore operation can include thedata blocks that are to be restored to a target client 102B. Althoughthe illustrated embodiment shows the client-side signature repository121 receiving the signatures from the media agent 144, the client-sidesignature repository 121 can receive the signatures from variouscomponents of the storage system 100. For example, the client-sidesignature repository 121 can receive the signatures from the componentinitiating the restore request, from the client 1028, or can generatethe signatures itself.

In some embodiments, a component of the storage system 100 includes anindex of the restore data set, which can include the signaturescorresponding to the data blocks in the restore data set as well as amapping of the organization of the restore data set. The index can be acopy data set index that is generated during the secondary copyoperation, for example, or can be derived therefrom. In certain otherembodiments, the client-side signature repository 121 already has a copyof the index and the index is therefore not sent from the secondarystorage subsystem 118 to the primary storage subsystem 117. Forinstance, the client-side repository 121 in some cases retains copies ofindexes associated with secondary copy operations for later use in therestore operation.

Once the client-side signature repository 121 receives the signatures ofthe data blocks in the restore data set, the client-side signaturerepository 121 (2) identifies data blocks in the restore data set thatare already located in the primary storage subsystem 117. In theillustrated embodiment, the client-side signature repository 121identifies copies of the data blocks in the restore data set thatalready reside in the target client 102B. However, in other embodiments,the system can implement a collaborative restore operation (FIG. 10) inwhich data blocks are sourced from non-target clients 102 instead of orin addition to the target client 102.

For data blocks for which copies do not reside in the primary storagesubsystem 117 (e.g., where no corresponding signature was found in theclient-side signature repository 121, or where the information in theclient-side repository 121 otherwise indicates the data block is not inprimary storage), the client-side signature repository 121 (or otherappropriate component) (3) requests copies of the data blocks from themedia agent 144. For instance, the client-side signature repository 121can request the data blocks individually from the media agent 144 and/orcan bundle multiple data block requests together. In turn, the mediaagent 144 can (4) request and receive the data blocks from the storagedevice 108 and the client-side signature repository 121 can (5) receivethe data blocks from the media agent 144. Similar to the client-sidesignature repository 121, the media agent 144 can send the data blocksindividually or bundle multiple data blocks together.

Once the client-side signature repository 121 has identified thelocation of the data blocks within primary storage and received the datablocks not in primary storage from secondary storage, the client-sidesignature repository 121 can (6) forward information to the client 102that is sufficient to perform the restore operation. For instance,references (e.g., location information) to the data blocks in therestore set that already reside in the target client 102B are forwardedto the target client 1028 along with copies of the data blocks receivedfrom the secondary storage subsystem 118. In addition to the locationinformation of the data blocks stored in the primary storage device 104and the data blocks received from secondary storage subsystem 118, theclient-side signature repository 121 can transmit a restore data setindex that provides information regarding how the data blocks in therestore data set are organized. The target client 102B can use thereceived location information, received data block copies, and/orreceived restore data set index to create the restored data set.

One skilled in the art will appreciate that all of the components ofstorage system 100 are not necessary to store and restore data blocks,and that the processes described herein can be implemented in any numberof ways without departing from the spirit and scope of the description.For example, in an embodiment, the client-side signature repository 121does not perform any of the processing steps. In such an embodiment, theclient 102B or media agent 144 can query the client-side signaturerepository 121 for the signatures corresponding to the data blocksinvolved in the restore operation. The client 102B or media agent 144can then identify the data blocks stored in primary storage as describedpreviously. In some embodiments, the client-side signature repository121 can simply transmit the signatures of the data blocks not located inprimary storage to the media agent 144 without requesting the datablocks in return. In response, the media agent 144 can transmit the datablocks not found in primary storage directly to the client 102B forrestore via a network, bypassing the client-side signature repository121.

FIG. 10 is a state diagram illustrative of the interaction between thevarious components of a storage system 100 with respect to an exemplarycollaborative restore operation. For purposes of the example, theillustrated embodiment has been simplified to include interactionbetween the clients 102, one media agent 144, and one storage device108. In other embodiments, any of the media agents 144 and any of thestorage devices 108, alone or in combination, can be used for performinga collaborative restore operation on any combination of the clients 102.Although in the illustrated embodiment the client-side signaturerepository 121 is associated with multiple clients, in some embodiments,each of the clients 102 is associated with its own client-side signaturerepository 121.

As described in greater detail above, with reference to FIGS. 8 and 9,the storage system 100 initiates a restore request and the CSR 121 (1)receives signatures of data blocks in a restore data set that are to berestored to a target client and (2) identifies data blocks in therestore data set that are located in primary storage. In thisembodiment, the data blocks located in primary storage refers to all ofthe data blocks located in any of the clients 102A, 102B, 102C, or otherclients for which the client-side signature repository 121 storessignature blocks. However, as mentioned previously, in some embodiments,the data blocks located in primary storage can refer to only the datablocks located in a single client.

As discussed in greater detail above, with reference to FIGS. 8 and 9,the data blocks located in the primary storage subsystem 117 can beidentified using the signature blocks stored in the client-sidesignature repository 121. Once identified, the location information ofthe data blocks located in the primary storage subsystem 117 can also beretrieved, as described previously. For example, the client-sidesignature repository 121 can review the location information 218 of theentries 214 of the signature block 206 corresponding to the data blocksin the restore data set to identify one or more locations within theprimary storage subsystem 117 where the data block is located.

In this example, some of the data blocks to be restored to a firstlocation in the client 102B can be located in a second location in theclient 102B and/or in one or more of the other clients 102A, 102C.Accordingly, the client-side signature repository 121 can identify whichof the different locations will be used as within the primary storagesubsystem 117 to source to each data block based on a data sourcingpolicy, which will be described in greater detail below with referenceto FIG. 12.

Once the sources of the respective data blocks in the restore data sethave been identified, the client-side signature repository 121 (3A),(3B) requests and receives the data blocks to be used in the restorefrom the source client(s) 10 based on the data sourcing policy. In othercases, the data blocks are forwarded directly to the target client 102Bwithout first being transmitted to the client-side repository 121. Inaddition, the client-side signature repository 121 (3C) requests thedata blocks not already residing in the primary storage subsystem 117from the media agent 144, and the media agent 144 in turn requests andreceives (4) the data blocks from the storage device 108. Theclient-side signature repository 121 then receives (5) the data blocksfrom the media agent 144. In some cases, even if a copy of one or moreof the data blocks in the restore data set resides in the primarystorage subsystem 117 (e.g., in one of the non-target clients 102A,102C), the data block may nonetheless be sourced from the secondarystorage subsystem 118. For instance, the sourcing policy may dictatethat the client(s) 102 that stores the copy of the data block should notbe interrupted for the purposes of accessing the data block, such aswhere that client 102 is performing critical tasks or the like.

In the illustrated embodiment, once the data blocks have been receivedfrom the clients 102A, 102C and secondary storage, the client-sidesignature repository 121 can (6) transmit the data to the client 102B.The target client 102B may compile the restore data set by combining thereceived data with any data blocks that are sourced from the targetclient 102B, and restore the data set to the primary storage device 104,completing the restore operation. In other configurations, the entirerestore data set is compiled at the client-side repository 121 and thencommunicated to the target client 102B.

In some embodiments, the client-side signature repository 121 is alsoupdated in view of the data that is copied to the primary storagesubsystem 117 during the restore operation. For instance, theclient-side signature repository 121 can be updated to reflect datablocks that were received from the secondary storage subsystem 118during the restore and written to the primary storage device 104associated with the target client 102B. Moreover, the client-sidesignature repository 121 can be updated to reflect copies of data blocksthat were communicated from any non-target clients and written to theprimary storage device 104 associated with the target client 1028.

One skilled in the art will appreciate that all of the components ofstorage system 100 are not necessary to store and restore data blocks,and that the processes described herein can be implemented in any numberof ways without departing from the spirit and scope of the description.For example, in an embodiment, the client-side signature repository 121does not perform any of the processing steps. In such an embodiment, theclient 102B or media agent 144 can query the client-side signaturerepository 121 for the signatures corresponding to the data blocksinvolved in the restore operation. The client 102B or media agent 144can then identify the data blocks stored in primary storage as describedpreviously. In some embodiments, the client-side signature repository121 can simply transmit the signatures of the data blocks not located inprimary storage to the media agent 144 without requesting the datablocks in return. In reply, the media agent 144 can bypass theclient-side signature repository 121 and transmit the data blocks notfound in primary storage directly to the client 102B for restore via anetwork. Similarly, the clients 102A, 102C can bypass the client-sidesignature repository 121 and transmit the data blocks to be restoredfrom the clients 102A, 102C directly to the client 102B via a network.Furthermore, in some embodiments, multiple client-side signaturerepositories 121 can be used. For example, each client 102 can beassociated with its own client-side signature repository 121. Theclient-side signature repositories 121 can communicate with each otherduring the restore to effectuate the various processes described above.

FIG. 11 is a flow diagram illustrative of an embodiment of a routine1100 implemented by a storage system 100 for performing a collaborativerestore operation. One skilled in the relevant art will appreciate thatthe elements outlined for routine 1100 may be implemented by one or morecomputing devices/components that are associated with the storage system1100. For example, routine 1100 can be implemented by any one, or acombination of, the storage manager 140, one or more clients 102, theclient-side signature repository 121, one or more media agents 144,and/or one or more storage devices 108.

At block 1101, the storage system 100 receives a request to restore arestore data set to a target client 1028.

At block 1102, the client-side signature repository 121 receivessignatures of data blocks in the restore data set. The client-sidesignature repository 121 may be shared by the clients, or separatededicated client-side signature repositories may be associated with someor all of the clients 102. At block 1104, the agent of the client-sidesignature repository 121 reviews the information in the client-sidesignature repository 121 to identify data blocks in the restore data setthat are located in in the primary storage subsystem 117 in any of themanners described herein.

For each data block in the restore data set that is located in theprimary storage, the agent 202 of the client-side signature repository121 determines whether the data block already resides in the primarystorage device(s) 104 associated with the target client 1028, at block1106. For instance, where signature information is organized insignature blocks 206, the agent 202 of the client-side signaturerepository 121 can review the entries 214 of the signature blocks 206corresponding to the data blocks located in the primary storagesubsystem 117 to determine whether the data block is located in theprimary storage device(s) 104 associated with the target client 102B.For example, the location information 218 in each entry 214 can includea client ID indicating which client 102 includes a copy of the datablock and/or indicating the physical location of the data block withinthe storage device 104 associated with the client 102.

If it is determined that the data block is located in the storage device104 associated with the target client 102B, the agent 202 of theclient-side repository 121 can identify the location of the data blockat block 1108, e.g., by referring to information provided in thelocation field 218 in the entry 214 of the corresponding data block. Onthe other hand, if the storage system 100 determines that the data blockis not located in the target client 102B, the storage system 100 canrequest and receive the data block from another client 102, at block1110. The source client 102 can be determined based on a data sourcingpolicy, which will be described in greater detail below with referenceto FIG. 12.

The agent of the client-side repository 121 also identifies data blocksnot located in the primary storage subsystem 117, and those data blocksare requested and received from the secondary storage subsystem 118. Insome cases where a data block does not exist in the storage device 104associated with the target client 102B, even if a copy of the data blockdoes reside in one of the other clients 102, it is nonetheless sourcedfrom the secondary storage subsystem 118 based on the sourcing policy.In some other embodiments, the sourcing policy specifies that, even if acopy of the data block is found in the storage device 104 associatedwith the target client 1028, the data block is still sourced from one ofthe non-target clients 102 or from the secondary storage subsystem 118.

At block 1112 the data set is restored to the primary storage device 104of the target client 1028.

One skilled in the art will appreciate that routine 1100 can includefewer, more, or different blocks than those illustrated in FIG. 11.

FIG. 12 is a flow diagram illustrative of an embodiment of a routineimplemented by a storage system 100 for determining a location fromwhich to source data blocks for a storage operation. One skilled in therelevant art will appreciate that the elements outlined for routine 1210may be implemented by one or many computing devices/components that areassociated with the storage system 1210. For example, routine 1210 canbe implemented by any one, or a combination of, the storage manager 140,one or more clients 102, the client-side signature repository 121, oneor more media agents 144, and/or one or more storage devices 108.

At block 1212, the storage system 100 identifies a data block involvedin a storage operation that is associated with a target client 102. Thestorage operation can include, but is not limited to, a copy operation,restore operation, other storage operation, etc. The identified datablock can include a data block to be restored, that is involved in thecopy operation, and/or involved in another storage operation.

At block 1214, the storage system 100 identifies the signature of thecurrent data block. In some embodiments, the storage system 100identifies the signature by generating the signature of the data block.In certain embodiments the storage system 100 identifies the signatureof the data block by retrieving the signature information from theclient-side signature repository 121, or other location.

At block 1216, the storage system 100 identifies the instances of thedata block that reside within the primary storage subsystem 117. In someembodiments, where the signature information is organized as signatureblocks 206 in the manner described herein, the storage system 100identifies the instances of the data block by reviewing the signatureblocks 206. As described in greater detail above, with reference toFIGS. 2A, 2B, and 3, the signature blocks stored in the client-sidesignature repository 121 can include an instances field 210 thatidentifies the number of instances of a particular signature 208.Moreover, the signature block 206 can include location information ofthe data block in the location field 218 and access/priority informationof the data block in the access/priority field 220 of each instance ofthe data block.

At block 1208, the storage system 100 accesses a data sourcing policy.The data sourcing policy can be located in one or more components of thestorage system 100. For example, the data sourcing policy can reside inthe storage manager 140, one or more clients 102, the client-sidesignature repository 121, one or more media agents 144, and/or one ormore storage devices 108. In some embodiments, portions of the datasourcing policy reside in different components of the storage system100.

At block 1206, the storage system 100 may have determined that aparticular data block resides in multiple sources within the primarystorage subsystem 117 (e.g., data stores associated with multiple onesof the clients 102). The data sourcing policy can be used to determinefrom which source the data block should be retrieved for the particularstorage operation. For example, during a copy operation when multipleinstances of a data block that is unique to primary storage (i.e., notlocated in secondary storage) are located in the primary storagesubsystem, the storage policy can be used to determine which source toretrieve the data block from for transmission to the secondary storagesubsystem 118. Similarly, during a restore operation, where multiplecopies of a data block reside within the primary storage subsystem 117,the data sourcing policy can indicate from which source to retrieve thedata block to be restored.

The data sourcing policy can specify that the determination of thesource of the data block based on a variety of factors. For instance,characteristics associated with the different sources (e.g.,characteristics associated with the clients 102 or the primary storagedevices 104), network information, and/or relative priority informationassociated with the sources may be used. For example, the data sourcingpolicy can compare the relative speeds of the different availablesources, estimated total expected times to retrieve the particular datablock from the available sources, or software or firmware versionsresiding on the available sources to determine which source is bettersuited to be involved in the storage operation, etc. The data sourcingpolicy can also specify that the relative proximity of the availablesources to the target client and/or available network bandwidth betweenthe available sources and the target client 102B should be factored into determine the preferred source. In addition, the data sourcing policycan specify that if one or more data blocks are to be retrieved from aparticular source client 102, that source client is a preferred sourcefor subsequent data blocks.

In some embodiments, the data sourcing policy reviews a priorityindication associated with the sources. The priority indication canspecify the relative priority of a potential data block source (e.g.,client 102 and/or primary storage device 104) with respect to othersources. The priority indication can be a fixed value, or can bedetermined dynamically, e.g., based on a load associated with thesource, based on the number or types of processes being executed bysource, a user associated with the source, etc. For example, if onesource containing a copy of a data block has a higher priority thananother source, the data sourcing policy can specify that a source withthe lower priority should be used to retrieve the data block.Furthermore, the data sourcing policy can account for upcoming processesto be performed by the source. For example, if a source is about tobegin a processor intensive process, the data can be retrieved from adifferent source. In certain embodiments, the data sourcing policyselects the source that can most quickly provide the data block. Ingeneral, the sourcing policy can specify that any combination of theabove or other appropriate factors can be used in making the data blocksourcing determination.

At block 1210, the storage system 100 identifies a preferred sourcebased on the data sourcing policy. For instance, where the preferredsource is dynamically determined, e.g., on the fly and/or in real timeduring a storage operation, once the available sources of the data blockare identified, the accessed data sourcing policy is referred todetermine which of the sources is the preferred source for thatparticular storage operation.

On the other hand, where the preferred source is fixed or otherwisepredetermined, each time a signature block is updated in the client-sidesignature repository 121, the storage system 100 can access the sourcinginformation (e.g., review the entries of the signature block 206) todetermine the preferred sourcing order for retrieving the data block. Insome cases, different sourcing orders are specified, e.g., depending onthe type storage operation involved and the identity of the targetclient.

The preferred sourcing order can be stored in a separate field of thesignature block, or each entry can include a sourcing rank thatindicates its relative priority among the various potential data blocksources. For instance, in the event, both a top ranked (e.g., highpriority) source and another, lower ranked source maintain a copy of adata block, the lower ranked source is selected.

At block 1212, the storage system 100 accesses the data block from thepreferred source. In some embodiments, the source transmits the datablock to the target client 102B (e.g., for a copy operation), the mediaagent 144 (e.g., for a restore operation), and/or the client-sidesignature repository 121, etc., based on the storage operation.

One skilled in the art will appreciate that routine 1210 can includefewer, more, or different blocks than those illustrated in FIG. 12. Insome embodiments, the storage system 100 can omit block 1218 andidentify the preferred source without accessing the data block sourcingpolicy. For example, if the sources have been previously ranked, thestorage system can identify the preferred source by referring to thesignature block without accessing the data block sourcing policy.

FIG. 13 is a block diagram illustrative of an expanded view of anexample copy data set index 1302 stored in the storage system 100. Thecopy data set index 1302 can be located in one or more components of thestorage system 100. In the illustrated embodiment, the copy data setindex 1302 is located in the secondary storage subsystem 118 within themedia agent 144 and/or the storage device 108.

Further, the copy data set index 1302 can be generated in response to acopy operation associated with a client 102. The copy data set index1302 can include information that can be used by the storage system 100to identify the signatures of the data blocks involved in the copyoperation and/or determine how the identified data blocks are organized.The copy data set index 1302 can include information regardingsubstantially all of the data stored on a primary storage device(s) 104associated with a client 102, or of select data (e.g., particular filesor folders or of one or more subclients).

The copy data set index 1302 can include multiple data entries 1304.While a variety of organizational schemes are possible, in theillustrated organization, each entry 1304 provides information regardingthe signature of one or more data blocks in a copy data set. Forexample, each entry 1304 can include a signature field 1306 and a datablock ID field 1308.

The signature field 1306 can include a signature of one or more datablocks that are in the copy data set. The signature can be generated asdescribed previously with respect to FIGS. 1A-1J, 2A, 2B, and 3. In someembodiments, each entry 1304 corresponds to a different unique signatureof one or more data blocks that are in the copy data set. For example,if a particular copy operation involves 1,000 data blocks with a totalof 600 different signatures, the copy data set index 1302 can include600 different entries. In certain embodiments, each entry corresponds toan instance of each data block. For example, with continued reference tothe previous example, the copy data set index 1302 in such a case wouldinclude 1,000 entries corresponding to the 1,000 data blocks involved inthe storage operation.

The data block ID field 1308 can include identifiers for each data blockwith a signature that matches the signature in the signature field 1306.The identifiers can provide information regarding how the data blocksare related, such as the order of the data blocks with respect to oneanother. For example, the copy data set index 1302 for File A in theclient 102B, can indicate in the data block ID fields 1308 which datablock is first, second, third, and so on, so that when File A isrestored to client 102B, the client 102B will know how the data blocksare to be arranged. In the illustrated embodiment, Block1, Block3, andBlock5 all have the same signature (Signature1). Similarly, Block4 andBlock6 share Signature3. Block2 has a unique signature. In thisembodiment, Block1 corresponds to the first data block of the copyoperation, Block2 corresponds to the second data block of the copyoperation, etc. Accordingly, using the copy data set index 1302, thestorage system 100 can identify all of the signatures in the copy dataset index 1302, all of the data blocks corresponding to the signature,and the order of the data blocks with respect to each other.

The copy data set index 1302 can include additional information asdesired. For example, in some embodiments, the copy data set index 1302can include signature block reference relating the particular signaturein the copy data set index 1302 with a signature block in theclient-side signature repository 121. In some embodiments, the copy dataset index 1302 includes additional metadata (e.g., file and directorymetadata).

FIG. 14 is a flow diagram illustrative of one embodiment of a routine1400 implemented by the storage system 100 for executing a secondarycopy operation using a client-slide signature repository 121. Oneskilled in the relevant art will appreciate that the elements outlinedfor routine 1400 may be implemented by one or more computingdevices/components that are associated with the storage system 100. Forexample, the routine 1400 can be implemented by any one, or acombination of, the storage manager 140, one or more clients 102, theclient-side signature repository 121, one or more media agents 144,and/or one or more storage devices 108.

At block 1401, the storage system 100 receives a copy operation request.For example, the storage manager 140 can instruct the client 102,client-side signature repository 121, and/or media agent 144 to initiatethe copy operation. The request can occur in any of the mannersdescribed herein, such as automatically according to a schedule (e.g.,daily, weekly, monthly) specified in a storage policy. Alternatively,the copy operation can occur in response to user interaction with a userinterface. Furthermore, the copy operation request can includeinformation regarding a specific client whose data is to be copied, thespecific data (e.g., particular files, folders, or portions thereof)that are to be copied, specific type of operation (e.g., incrementalbackup, full backup, snapshot, and the like).

At block 1402, the storage system 100 identifies a copy data setassociated with the copy operation request.

In some embodiments, the client-side signature repository 121 includesan index of all the files, folders, etc., found on the clients 102 withwhich the client-side signature repository 121 is associated. Forexample, if the client-side signature repository 121 is associated withone client it can include an index of all the files, folders, etc.,found on the one client. If the client-side signature repository 121 isassociated with multiple clients it can include an index of all thefiles, folders, etc., found on the multiple clients. The copy data setindex can be used to identify which data blocks correspond to the copydata set, and how the data blocks are organized. In other cases, such anindex is stored on each client 102.

At block 1404, the storage system 100 identifies signature blocks thatcorrespond to the identified data blocks in the copy data set and thathave been modified since a previous copy operation (also referred to asa modified signature block). A modified signature block can indicatethat an entry has either been added or removed to the signature blocksince the previous copy operation, and that a copy of the correspondingdata block has either been added somewhere in primary storage orremoved. Furthermore, a modified signature block can indicate that thesecondary storage does not include references to all of the instances ofa particular data block and/or may not include the data block at all. Inthis way, the system can identify which data blocks already exist insecondary storage and which do not. If the data blocks already exist insecondary storage, significant time can be saved by during deduplicatedcopy operations, by transmitting signature block information as part ofa copy data set index, described below. The signature block informationcan indicate that another copy of the data block already exists in thesecondary storage, instead of transmitting the entire data block.

As mentioned previously, the identification of signature blocks thathave been modified since the previous copy operation can be done byreviewing the copy operation flag 212 of the signature block. Othermethods can be used to identify signature blocks that have been modifiedsince the previous copy operation. In some embodiments, the client 102,the client-side signature repository 121, and/or the media agent 144 caninclude an index that maps signatures of data blocks stored in a clientwith one or more files or folders stored in the client that have beenpreviously copied to the secondary storage subsystem. The index caninclude how many data blocks are used to form a particular file and howthe data blocks are organized within the file.

The storage system 100 can also use the age field 222 in the entries 214of the signature blocks 206 stored in the client-side signaturerepository to identify signature blocks that have been modified since aprevious copy operation. For instance, the storage system 100 cancompare information in the age field, such as creation date or edit datewith date information for a previous copy operation. If the age fieldindicates that the entry 214 was added after the previous copyoperation, the storage system 100 can determine that the signature blockhas been modified since the previous copy operation.

For each modified signature block, the storage system 100 determineswhether the modified signature block is a new signature block, asillustrated in decision block 1406. New signature blocks correspond tosignatures and/or corresponding data blocks do not exist in thesecondary storage subsystem 118 and/or signatures that did not exist inthe client-side signature repository 121 prior to the previous backup.Signature blocks that are not new can correspond to signatures and/orcorresponding data blocks that have been stored in the secondary storagesubsystem 118 in conjunction with a previous copy operation (e.g., aspart of a copy data set index or otherwise) and/or existed in theclient-side signature repository 121 prior to the previous backup. Thesystem 100 can determine whether the signature block is new in a varietyof ways. For instance, to determine whether the signature block is new,the system 100 can determine when the signature block was created. Ifthe signature block was created after a previous copy operation, thesignature block can be identified as new. In some embodiments, if thesignature block contains only one entry, and the one entry is a newentry, the signature block is identified as new. Furthermore, the systemcan refer to a copy operation flag in the signature block that indicateswhether the signature blocks has been part of a copy data set in a copyoperation (e.g., has already been backed up to secondary storage).Similarly, the system 100 can determine that the signature block is notnew in many different ways. For example, the system can determine thatthe signature block is not new when multiple entries are included in thesignature block, when the signature block was created prior to aprevious copy operation that included the corresponding data block, whenthe copy operation flag indicates that the signature block has not beenpart of a copy operation, or any number of other ways, or anycombinations thereof.

Upon determining that the modified signature block is a new signatureblock, the storage system 100 locates the data block corresponding tothe new signature block within the primary storage subsystem 117 asillustrated in block 1408. The storage system 100 can also identify thedata block corresponding to the signature found in the signature blockas a new data block. In some embodiments, the storage system locates thedata block within the client 102B. In certain embodiments, the storagesystem 100 locates the data block within one or more clients other thanclient 1028, such as client 102A and 102C.

Once the data blocks corresponding to the new signature blocks have beenidentified, the storage system 100 transmits the located data blocks andnew signature blocks to the secondary storage subsystem 118, asillustrated in block 1410. In some embodiments the storage system 100transmits portions of the new signature block but not the entiresignature block. In certain embodiments, the storage system 100 waitsuntil all modified signature blocks have been reviewed and transmitsmultiple located data blocks and multiple new signature blocks tosecondary storage. In some embodiments the storage system 100 transmitsall of the located data blocks and all of the new signature blocks tosecondary storage simultaneously.

If the storage system 100 determines that the modified signature blockis not a new signature block, the storage system 100 transmits themodified signature block to the secondary storage subsystem 118, asillustrated in block 512. By identifying the modified signature block asnot being a new signature block, the storage system 100 has determinedthat the corresponding signature that is being reviewed was stored inthe client-side signature repository 121 prior to the previous storageoperation and/or that the corresponding data block exists in thesecondary storage subsystem 118. Accordingly, only the signature blockor portions thereof (e.g., just the signature), and not the data blockitself, are transmitted to secondary storage, so that secondary storagecan update the maps and indices related to the client 102B.

One skilled in the relevant art will appreciate that routine 1400 caninclude fewer, more, or different blocks than those illustrated in FIG.14. For example, the storage system 100 can transmit a copy data setindex (FIGS. 13-14) to the media agent 144. The copy data set index caninclude signature information for all of the data blocks that correspondto the copy data set. In some embodiments, once the storage system 100identifies the signature blocks corresponding to the data blocks in thecopy data set and that have been modified since a previous copyoperation, the storage system 100 identifies which of the identifiedsignature blocks constitute new signature blocks, as describedpreviously. The storage system 100 then locates and transmits the datablocks corresponding to the new signature blocks to secondary storage.The storage system can also transmit the copy data set index to themedia agent, which includes the signature information for all of thedata blocks in the copy data set.

Further, the retrieved data (data blocks and/or signature blocks) can besent from their respective locations either individually or bundledtogether. In certain embodiments, a component of the storage system 100can bundle all the data blocks and/or signature blocks together ingroups prior to sending the data to secondary storage. Furthermore, acopy data set index can be generated or retrieved and sent to secondarystorage as well. The copy data set index can indicate how the variousdata blocks are related. For example, the copy data set index canindicate the order of the data blocks with respect to one another (e.g.,for a particular file, group of files, or other copy data set).

For any of the embodiments described herein, the copies of the datablocks residing in the primary storage subsystem 117 that are sourcedfor generating secondary copy data sets or restore data sets weregenerated by programs (e.g., software applications) executing on aclient 102 during normal operation. For example, the copies form aportion of a file, folder, or other type of primary data, and are notcache copies (e.g., copies made for the purpose of decreasing retrievaltime and removed on a first-in-first-out basis) of other data blocksstored on the target client 102.

It will be appreciated by those skilled in the art and others that allof the functions described in this disclosure may be embodied insoftware executed by one or more processors of the disclosed componentsand mobile communication devices. The software may be persistentlystored in any type of non-volatile storage.

Terminology

Conditional language, such as, among others, “can,” “could,” “might,” or“may,” unless specifically stated otherwise, or otherwise understoodwithin the context as used, is generally intended to convey that certainembodiments include, while other embodiments do not include, certainfeatures, elements and/or steps. Thus, such conditional language is notgenerally intended to imply that features, elements and/or steps are inany way required for one or more embodiments or that one or moreembodiments necessarily include logic for deciding, with or without userinput or prompting, whether these features, elements and/or steps areincluded or are to be performed in any particular embodiment.

Depending on the embodiment, certain acts, events, or functions of anyof the algorithms described herein can be performed in a differentsequence, can be added, merged, or left out altogether (e.g., not alldescribed acts or events are necessary for the practice of thealgorithms). Moreover, in certain embodiments, acts or events can beperformed concurrently, e.g., through multi-threaded processing,interrupt processing, or multiple processors or processor cores or onother parallel architectures, rather than sequentially.

Systems and modules described herein may comprise software, firmware,hardware, or any combination(s) of software, firmware, or hardwaresuitable for the purposes described herein. Software and other modulesmay reside on servers, workstations, personal computers, computerizedtablets, PDAs, and other devices suitable for the purposes describedherein. Software and other modules may be accessible via local memory,via a network, via a browser, or via other means suitable for thepurposes described herein. Data structures described herein may comprisecomputer files, variables, programming arrays, programming structures,or any electronic information storage schemes or methods, or anycombinations thereof, suitable for the purposes described herein. Userinterface elements described herein may comprise elements from graphicaluser interfaces, command line interfaces, and other suitable interfaces.

Further, the processing of the various components of the illustratedsystems can be distributed across multiple machines, networks, and othercomputing resources. In addition, two or more components of a system canbe combined into fewer components. Various components of the illustratedsystems can be implemented in one or more virtual machines, rather thanin dedicated computer hardware systems. Likewise, the data repositoriesshown can represent physical and/or logical data storage, including, forexample, storage area networks or other distributed storage systems.Moreover, in some embodiments the connections between the componentsshown represent possible paths of data flow, rather than actualconnections between hardware. While some examples of possibleconnections are shown, any of the subset of the components shown cancommunicate with any other subset of components in variousimplementations.

Embodiments are also described above with reference to flow chartillustrations and/or block diagrams of methods, apparatus (systems) andcomputer program products. Each block of the flow chart illustrationsand/or block diagrams, and combinations of blocks in the flow chartillustrations and/or block diagrams, may be implemented by computerprogram instructions. Such instructions may be provided to a processorof a general purpose computer, special purpose computer, or otherprogrammable data processing apparatus to produce a machine, such thatthe instructions, which execute via the processor of the computer orother programmable data processing apparatus, create means forimplementing the acts specified in the flow chart and/or block diagramblock or blocks.

These computer program instructions may also be stored in acomputer-readable memory that can direct a computer or otherprogrammable data processing apparatus to operate in a particularmanner, such that the instructions stored in the computer-readablememory produce an article of manufacture including instruction meanswhich implement the acts specified in the flow chart and/or blockdiagram block or blocks. The computer program instructions may also beloaded onto a computer or other programmable data processing apparatusto cause a series of operations to be performed on the computer or otherprogrammable apparatus to produce a computer implemented process suchthat the instructions which execute on the computer or otherprogrammable apparatus provide steps for implementing the acts specifiedin the flow chart and/or block diagram block or blocks.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the disclosure. Indeed, the novel methods and systems describedherein may be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the describedmethods and systems may be made without departing from the spirit of thedisclosure. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the disclosure.

1. (canceled)
 2. A method of maintaining a signature repository in adata storage system, the method comprising: maintaining a primarystorage signature repository associated with a primary storage subsystemwherein the primary storage signature repository comprises signatureblocks for one or more unique signatures associated with a plurality ofdata units stored in a native format in the primary storage subsystem;maintaining a secondary storage signature repository associated with asecondary storage subsystem wherein the secondary storage signaturerepository comprises signature blocks for one or more unique signaturesassociated with copies of the plurality of data units stored in thesecondary storage subsystem in a non-native backup format, wherein whena first data unit stored in a first storage location in the primarystorage subsystem has a same unique signature as a second data unitstored in a second storage location in the primary storage subsystem,modifying an associated signature block in the primary storage signaturerepository by: identifying the first storage location of the first dataunit in the primary storage subsystem with a first data unit entry; andidentifying the second storage location of the second data unit in theprimary storage subsystem with a second data unit entry.
 3. The methodof claim 2, further comprising storing in a signature block a firstclient identifier that identifies a first client device associated withthe first data unit, and a second client identifier that identifies asecond client device associated with the second data unit.
 4. The methodof claim 3, wherein the first client device uses a first data store inthe primary storage subsystem that is different than a second data storeused by the second client device.
 5. The method of claim 2, furthercomprising: receiving a query including a plurality of signatures;comparing the plurality of signatures included in the query withsignature blocks in the primary signature repository to identify a firstset of signatures received in the query that correspond to data unitsthat reside in a primary data store of at least one client computingdevice of a plurality of client computing devices; and for at least someof the plurality of signatures in the first set of signatures, accessingcorresponding data units from the primary data store of the at least oneclient computing device.
 6. The method of claim 5, further comprisingaccessing the corresponding data units from the secondary storagesubsystem for the plurality of signatures included in the query that arenot included in the first set of signatures.
 7. The method of claim 5,wherein the plurality of signatures included in the query correspond toa set of data units which represent a backed up version of a set of theplurality of data units that is to be restored to the primary data storeof the at least one client computing device.
 8. The method of claim 2,further comprising: in response to receipt of instructions to backup atleast a subset of the plurality of data units in the primary storagesubsystem, comparing a set of signatures corresponding to the subset ofdata units with entries in the primary storage signature repository;based at least in part on the comparing, identifying a set of matchingdata units that match the subset of data units; and accessing the set ofmatching data units for retrieval.
 9. The method of claim 7, furthercomprising: based at least in part on the comparing, identifying a firstgroup of data units of a subset of data units that do not have acorresponding matching data unit; and communicating the first group ofdata units to the secondary storage subsystem.
 10. The method of claim2, wherein the secondary storage subsystem comprises deduplicated data.11. The method of claim 2, wherein at least a portion of the primarystorage subsystem of at least one of a plurality of client computingdevices comprises deduplicated data.
 12. The method of claim 2, whereinthe secondary storage subsystem comprises deduplicated data.
 13. Astorage system, comprising: a signature repository agent executing onone or more processors, a primary storage signature repositoryassociated with a primary storage subsystem wherein the primary storagesignature repository comprises signature blocks for one or more uniquesignatures associated with a plurality of data units stored in a nativeformat in the primary storage subsystem; a secondary storage signaturerepository associated with a secondary storage subsystem wherein thesecondary storage signature repository comprises signature blocks forone or more unique signatures associated with copies of the plurality ofdata units stored in the secondary storage subsystem in a non-nativebackup format, wherein when a first data unit stored in a first storagelocation in the primary storage subsystem has a same unique signature asa second data unit stored in a second storage location in the primarystorage subsystem, the signature repository agent modifies an associatedsignature block in the primary storage signature repository to comprise:a first data unit entry that identifies the first storage location ofthe first data unit in the primary storage subsystem; and a second dataunit entry that identifies the second storage location of the seconddata unit in the primary storage subsystem.
 14. The storage system ofclaim 13, wherein the associated signature block further comprises afirst client identifier that identifies a first client device associatedwith the first data unit, and a second client identifier that identifiesa second client device associated with the second data unit.
 15. Thestorage system of claim 14, wherein the first client device uses a firstdata store in the primary storage subsystem that is different than asecond data store used by the second client device.
 16. The storagesystem of claim 13, wherein the signature repository agent is furtherconfigured to: receive a query from the secondary storage subsystem, thequery including a plurality of signatures; compare the plurality ofsignatures with signature blocks in the primary signature repository toidentify a first set of signatures from the plurality of signatures thatcorrespond to data units of the plurality of data units that reside in aprimary data store of at least one client computing device of aplurality of client computing devices; and for at least some signaturesin the first set of signatures, request corresponding data units fromthe at least one client computing device.
 17. The storage system ofclaim 16, wherein the signature repository agent to accesses data unitsfrom the secondary storage subsystem for the plurality of signaturesthat are not included in the first set of signatures.
 18. The storagesystem of claim 16, wherein the plurality of signatures included in thequery correspond to a set of data units which represent a backed upversion of a set of the primary plurality of data units that is to berestored to the primary data store of the at least one client computingdevice.
 19. The storage system of claim 13, wherein in response toreceipt of instructions to backup at least a subset of the plurality ofdata units in the primary storage subsystem, the signature repositoryagent compares a set of signatures corresponding to the subset of dataunits with entries in the primary storage signature repository and basedat least in part on the comparing, identifies a set of matching dataunits that match the subset of data units and accesses the set ofmatching data units for retrieval.
 20. The storage system of claim 19,wherein based at least in part on the comparing, the signaturerepository agent identifies a first group of data units of a subset ofdata units that do not have a corresponding matching data unit, andcommunicates the first group of data units to the secondary storagesubsystem.
 21. The storage system of claim 13, wherein at least aportion of the primary storage subsystem associated with at least one ofa plurality of client computing devices comprises deduplicated data.